The Olympic football tournament is almost set to kick off in Rio de Janeiro. Here is a preview of all 16 teams.
GROUP A
BRAZIL: The Brazilians are red-hot favourites to at last win the only title they are lacking, both because of the depleted competition and because they are taking it so seriously. For many Brazilians, the men's football tournament will be the most important part of the Games. Moreover, after years of disappointment, Brazil need something special to bring the fans back onside.
MANAGER: Rodrigo Micale had taken charge of Olympic preparation but was due to step down to the assistant role until senior national team coach Dunga was sacked at the Copa Centenario. Replacement Tite opted to concentrate on World Cup qualification, so Micale has been thrust into the limelight. Known for being down-to-earth and forward-thinking, he is creating a positive impression.
STAR PLAYER: Without a doubt, Neymar is the biggest star in the entire football tournament and has become one of the poster boys for the Games. Brazil chose to not take him to the Copa Centenario so he would be available for the Olympics. He's set to form a mouth-watering attacking trio with the young lions, Gabriel Jesus and Gabriel Barbosa.
OVER-AGE PLAYERS: With the exception of Neymar, Brazil have had some bad luck. Their goalkeeper, 38-year-old Fernando Prass, had to pull out on the eve of the competition, with Weverton of Atletico Paranaense quickly drafted in. Winger Douglas Costa also went down to an injury; his replacement, Renato Augusto, will have to compete with Felipe Anderson for a place in the starting line up. -- Tim Vickery
PREDICTION: Winners
SOUTH AFRICA: South Africa beat Brazil on their only previous Olympic Games outing in 2000 but astonishingly failed to get past the first round. They face the Brazilians again in their opening game but have sights set on Denmark and Iraq for the points to get them through to the next round. Prodigy Phakamani Mahlambi, who might have been a star of the tournament, misses out after suffering a serious injury, which hampers South Africa's chances.
MANAGER: The 54-year-old Owen da Gama played professionally in Belgium and Ireland in an era when not many South Africans got an opportunity overseas. He has coached only at clubs domestically (Platinum Stars, Orlando Pirates and Bloemfontein Celtic) and got the Under-23 job on the basis of his role as assistant to South Africa coach Ephraim Mashaba.
STAR PLAYER: Keegan Dolly is the captain of the side and a speedy winger dreaming of a chance to pit his wits against Neymar. He has been an integral part of the success of Mamelodi Sundowns in winning the South African league in May and in the last days progressing to the semifinals of the African Champions League.
OVERAGE PLAYERS: The need to strengthen the side to defend set pieces was the basis of Da Gama's choice of Itumeleng Khune and Mulomowandau Mathoho, both from Kaizer Chiefs. Khune is South Africa's captain and most capped goalkeeper, and "Tower" Mathoho a lanky centre-back who is a regular for the senior side. -- Mark Gleeson
PREDICTION: Group stage
IRAQ: It's a tough group for the team that finished fourth at the 2004 games in Athens, and preparations are often an issue for Iraq, yet the country has some extremely talented players. With hosts Brazil up second, Iraq need to get something from the game against Denmark, but in the end, the last eight is probably beyond the Lions of Mesopotamia.
MANAGER: Abdul Ghani Shahad got the job last year after domestic success with Naft Al-Wasat. He has impressed bosses in Baghdad enough to have also been handed the reins of the senior team in April. Being in charge of both teams means those who impress in Rio might get a crack at qualification for the 2018 World Cup.
STAR PLAYER: Dhurgham Ismail is only 21 yet has already established himself as one of the top left-backs in Asia, though he is also comfortable playing further up the pitch. Standout performances defending and going forward at the 2015 Asian Cup with the senior team helped broker a deal with Turkey team Rizespor.
OVERAGE PLAYERS:The coach has chosen three to bolster the spine of the team. Hard-working striker Hammadi Ahmad will lead the line, while big centre-back Ahmad Ibrahim will help deal with threats from the opposition. Saudi Arabia-based Saad Abdul-Amir will act as midfield anchor -- tidy in possession and intelligent in position. -- John Duerden.
PREDICTION: Group stage
DENMARK: Denmark have underwhelmed the past 50 years, appearing at two Olympics since 1960, but they finished runners-up that year and have silver and bronze medals to their names. A medal looks unlikely this time, though they should have enough to finish behind Brazil in a group that includes South Africa and Iraq. A quarterfinal defeat to Nigeria or Colombia seems a reasonable outcome.
MANAGER: U21 coach Niels Frederiksen will guide Denmark in Brazil. It will be his first major tournament since he was appointed to the position in August 2015, prior to which he was in charge at local clubs Lyngby and Esbjerg. Before he took over the former's first team, he worked at a bank while coaching the youth players.
STAR PLAYER: Fulham's Lasse Vigen Christensen was a bright spark in an underwhelming season for the Cottagers last year, and the all-action midfielder, who has captained the U21s, will hope the Olympics are an effective bridge to caps at senior level. Red Bull Leipzig forward Yussuf Poulsen, who will play Bundesliga football this season, is also worth watching.
OVERAGE STARS: Eddi Gomes might seem one of Denmark's most obscure exports, but the 27-year-old centre-back, who was born in Guinea-Bissau and now plays in China for Henan Jianye, played under Fredriksen at Esbjerg and is trusted for their Olympic campaign. Also involved are 25-year-old winger Emil Larsen, who has rejoined Lyngby from Columbus Crew, and Brentford striker Lasse Vibe, 29, who scored 14 Championship goals the past season. -- Nick Ames.
PREDICTION: Quarterfinals
GROUP B
SWEDEN: There might be no Zlatan Ibrahimovic, even though the Manchester United forward was named in the preliminary squad, but Sweden have reason to feel confident. Six of the squad that became European U21 champions last year will travel to Brazil, and their 23-man roster includes a number of players with experience in good leagues.
MANAGER: Hakan Ericson led Sweden's U21s to that famous success a year ago and is now tasked with masterminding a similarly against-the-odds victory. He comes of fine footballing stock: His father, Georg, managed the senior national team between 1971 and 1979 and led them to two World Cups.
STAR PLAYER: Mikael Ishak did not make the grade during spells in Germany and Italy earlier in his career, but still just 23, the striker can use these Games to make good on his early promise. Now with Randers in Denmark, Ishak scored 13 goals last season and notched twice in the UEFA U21 Championship-winning campaign. More of the same, and he could yet make a splash at a higher level.
OVERAGE STARS: Captain Alexander Milosevic, a mainstay of the U21s now aged 24, is the standout name, and the Besiktas centre-back will be a vital influence. Another hero from last year, Abdul Khalili -- also Turkey-based, with Mersin Idmanyurdu -- joins him in the squad, but 26-year-old Astrit Ajdarevic, once of Liverpool, Leicester and Charlton, is the oldest member of the party -- Nick Ames.
PREDICTION: Group Stage
COLOMBIA: Colombia booked their place in March after coming through a playoff with the United States. They count on a talented U23 generation, though injury has robbed them of towering centre-back Yerry Mina, and lithe attacker Marlos Moreno, this year's South American star, was not available. Even so, they have an interesting blend, and a medal is not out of the question.
MANAGER: Carlos Restrepo, always referred to by his nickname ("Pisces"), is a youth development specialist who has been in charge of Colombia's U20 side for more than four years. In 2013, they won the South American championship at the level, and several of the graduates from that side are in Brazil. He has worked extensively in Central America as well as at home.
STAR PLAYER: Teofilo Gutierrez is a centre-forward who mixes attacking threat with a certain braggadocio. The combination has brought him goals and headlines in five countries. He was part of the Colombia side that reached the World Cup quarterfinals for the first time in Brazil two years ago. He might now be aiming to take them even higher in the Olympics.
OVERAGE PLAYERS: Alongside Gutierrez, one of three dangerous centre-forwards in the squad, there is winger Dorlan Pabon, fast with a rocket shot, who has been strangely neglected by the senior Colombia side the past few years. To organise the defence, there is the solid common sense of centre-back William Tesillo. -- Tim Vickery
PREDICTION: Semifinals
NIGERIA: Nigeria won the African U23 Championship in Senegal in November and an Olympic Games place with it, in yet another triumph for the giant West African country in age-group competition on the continent. Their gold medal triumph of 1996 remains a high point for the country, and the need to emulate that feat puts pressure on the self-styled "Dream Team".
MANAGER: Former Super Eagles striker Samson Siasia took the Nigerians to the silver medal at the 2008 Games in Beijing and is in a second spell in charge of the U23 side. A Ligue 1 winner in his playing days with Nantes, the 48-year-old Siasia, who keeps a residence in the U.S., was fired as Nigeria's senior team coach after failure to qualify for the 2012 African Nations Cup.
STAR PLAYER: Azubuike Okechukwu has already been capped at full international level, though still aged 19 and playing in obscurity in Turkey. He was named the best player at last year's African U23 Championship and has recently been linked with a move to Monaco.
OVERAGE PLAYERS: John Obi Mikel is likely to be almost a fatherly figure in the squad, but he had little participation in the pre-tournament preparations. Goalkeeper Daniel Akpeyi, who plays club football in South Africa, is usually the backup for the senior side and is brought in to strengthen a consistent weak point.
PREDICTION: Group stage
JAPAN: This version of Samurai Blue was deeply hurt at missing out on bronze in 2012, especially at the hands of bitter rivals South Korea. There was some revenge in the final of the Asian U23 championships, but repeating the bronze medal success of 1968 would be rewarding indeed. It is a tough group, but Japan have the talent and motivation to get to the knockout stage.
MANAGER: Makoto Teguramori. The 48-year-old had some success with unfashionable J. League side Vegalta Sendai before taking the job U-23 job in 2014. The confident Teguramori has had success this year already in leading his charges to the Asian title in January and has a good rapport with the players.
STAR PLAYER: Takuma Asano. The 21-year-old would have been one to watch without the recent surprise move to Arsenal. Fast with a liking for running at defenders, it will be fascinating to see how the former Sanfrecce Hiroshima forward performs with the extra attention on and off the pitch.
OVERAGE PLAYERS: Despite having numerous players active in Europe, all three are based in the J. League. Urawa Reds star Shinzo Koroki adds experience to the forward line, though he failed to find the net during a stop-start career with the senior side. Elegant centre-back Tsukasa Shiotani has also been called, along with Gamba Osaka left-back Hiroki Fujiharu. -- John Duerden.
PREDICTION: Quarterfinals
GROUP C
FIJI: All, especially South Korea, would be well-advised to take Fiji seriously. The team has come up together through the Under-20 World Cup and has a team spirit second to none, led by a coach who knows their strengths well. They won't get out of the group, but they can stop others from doing so.
MANAGER: Frank Farina has been around the block quite a few times as player and manager, playing for and then coaching the Australian national team. He led the Socceroos to the 2000 and 2004 Oceania titles and took Fiji's Under-20 team to the 2015 World Cup, which included a 3-0 win over Honduras.
STAR PLAYER: Iosefo Verevou. Big and powerful with so much more to his game, the striker is expected to be landing an overseas contract soon -- perhaps once the tournament is finished. The 2015 Fiji Sportsman of the Year impressed at the Under-20 World Cup last year and is expected to do so once again in Rio.
OVERAGE PLAYERS: Farina has returned to the A-League to bolster his squad with the only overseas-based player in 28-year-old Roy Krishna, who plays up front for Wellington Phoenix and has a fine scoring record for the senior team. Simione Tamanisau will be between the sticks, while Alvin Singh bolsters the backline. -- John Duerden.
PREDICTION: Group stage
SOUTH KOREA: South Korea took bronze at the 2012 games and would be delighted with a similar haul this time around, as a podium finish means exemption from military duty for the players. South Korea are packed full of attacking talent but have weaknesses at the back. Take three points against Fiji in the opening game, and the quarterfinals are within reach.
MANAGER: Shin Tae-yong is not only the assistant of the senior national team, but he also led Seongnam FC to the 2010 Asian Champions League title. Confident and still relatively young, he has compared himself to Jose Mourinho, but this snappy dresser and sharp tactician is more of a Joachim Low.
STAR PLAYER: Kwon Chang-hoon. Gamba Osaka coach Kenta Hasegawa recently said the 22-year-old was the future of Korean football, and the attacking midfielder has been on the shopping list of Bundesliga clubs for some time. A standout at the Asian Under-22 Championships despite not being fully fit, Kwon scores goals, creates goals and makes things happen.
OVERAGE PLAYERS: Son Heung-min has not always shown his talent for the senior side, but the Tottenham attacker is expected to lead the charge of the young Taeguk Warriors. FC Porto's Suk Hyun-jun will lead the line (if he recovers from injury) with China-based Jang Hyun-soo in the middle. -- John Duerden.
PREDICTION: Group stage
MEXICO: The reigning Olympic champions have pumped money into youth development in recent years, and El Tri should again be one of the contenders for a medal at Rio. Although this squad is arguably not as good or experienced as the one at London 2012, there is still plenty of quality. Expect Mexico to reach the semifinals.
MANAGER: Raul "Potro" Gutierrez guided this same generation of players to the U17 World Cup in 2011 and needs a strong Olympics to prove that he is a candidate for the senior team job further down the line. Gutierrez stays true to Mexico's traditionally technical and possession-based style of play.
STAR PLAYER: Hirving Lozano. The flying winger is already a fixture with the national team and is a step ahead of his peers, though centre-back Cesar Montes and midfielder Rodolfo Pizarro are close behind. There have been rumours linking the 20-year-old Pachuca player with Manchester United, but the club are unlikely to be the only European institution with scouts watching Lozano in Rio.
OVERAGE PLAYERS: Mexico struggled to get permission for the likes of Javier Hernandez and Andres Guardado. Instead, Gutierrez has gone for pragmatic, domestic picks. Toluca goalkeeper Alfredo Talavera provides proven quality in goal; Tigres left-back Jorge Torres Nilo fills a hole in a much-needed position, while Oribe Peralta already has an Olympic gold to his name and brings both experience and goals. -- Tom Marshall.
PREDICTION: Final
GERMANY: Enter the Olympic tournament for the first time since 1988, when Germany came in third in Seoul. That was their second bronze medal at this level, and they have a chance to emulate that in Brazil, though South Korea and Mexico have the firepower to cause problems in the group stage. A semifinal appearance looks likely -- and if all goes to plan it would be against host nation Brazil. Ring any bells?
MANAGER: Horst Hrubesch has coached Germany at various youth levels for a decade-and-a-half, and after a spell with the U19s, he took charge of the U21s for a second stint in 2013. Prior to his work in the national team setup, the 65-year-old, who was a prolific striker in his playing career, managed the likes of Wolfsburg, Dynamo Dresden and Samsunspor.
STAR PLAYER: Schalke 04 schemer Max Meyer should be one of the most exciting attacking talents at these Games. The diminutive attacking midfielder, who has been capped at senior level, does not turn 21 until September and already has two years of Bundesliga and Champions League experience under his belt. A creative force with quick feet and an eye for goal, Mayer has shone throughout the youth levels for Germany and can be expected to do the same in Brazil. Borussia Dortmund's Matthias Ginter and Arsenal winger Serge Gnabry are among the other familiar names selected.
OVERAGE STARS: A strong-looking overage trio includes the Bender twins, Lars and Sven, who have 26 senior caps between them and, at 27 years old, a wealth of top-level experience with Bayer Leverkusen and Borussia Dortmund, respectively. Another 27-year-old, striker Nils Petersen, had a superb season with Freiburg last season, as they won Germany's second tier, and is rewarded with his first international call-up since he had two U21 caps in 2009. -- Nick Ames.
PREDICTION: Semifinals
GROUP D
HONDURAS: There is a generational shift in the full Honduras national team, and much is expected of this batch of players. In truth, they will struggle to get out of a group that includes Argentina and Portugal, but it would be a surprise if Los Catrachos were heavily beaten. Honduras defeated the United States in qualifying and shouldn't be underestimated.
MANAGER: Colombian Jose Luis Pinto thrives as the underdog against the big names, as he showed when he guided Costa Rica to the 2014 World Cup quarterfinal. A true student of the tactical side of the game at international level, Pinto will make sure his side is set up to be very difficult to beat.
STAR PLAYER: Alberth Elis. The hero of qualifying with two goals against the U.S., Elis is a forward who can play in the centre or on the right, with pace, trickery and a physical presence. There have already been rumours of interest from Everton, as well as clubs in Spain, MLS and Mexico and the 20-year-old -- already a full international -- is likely to move on from current club Olimpia. Also keep an eye out for right-back Kevin Alvarez.
OVERAGE STARS: Pinto decided to take only two overage players. Winger Romell Quioto has been in and out of the national team and provides a strong option on the left, while 29-year-old Johnny Palacios provides defensive solidity. Even though Antony "Choco" Lozano is 23, he has 20 full national team caps under his belt and will be relied on up front -- Tom Marshall.
PREDICTION: Group stage
ALGERIA: Algeria resisted the temptation to dip into the star-studded senior side for three headline reinforcements for their squad and opted instead to keep the continuity of the qualifying campaign. Unusually for the Algerians, who draw the majority of their playing resources from the Diaspora in France, this is a majority homegrown and home-based selection.
MANAGER: The 56-year-old Swiss Pierre-Andre Schurmann was contracted by the Algerian federation with Olympic qualification specifically in mind, given his success with Switzerland at U17 level (2002 European champions). His other coaching honours are the 1999 Swiss Cup, during his tenure at Lausanne Sport, which included eliminating Ajax in the UEFA Cup. He also coached at Sion.
STAR PLAYER: French born Rachid Ait-Atmane came through the junior ranks at Racing Lens along with the likes of Raphael Varane and Geoffrey Kondogbia. The midfielder helped Gijon win promotion to La Liga the season before last and featured in half their matches in the top-flight in their last campaign.
OVERAGE STARS: There had been extensive discussion with Riyad Mahrez about participating in Rio, but the Leicester City star and the federation did not reach an agreement. In the end, Schurmann settled for uncapped defender Abdelghani Demmou, midfielder Sofiane Bendebka and striker Baghdad Bounedjah, who plays in Qatar. -- Mark Gleeson.
PREDICTION: Group stage.
PORTUGAL: Even if we should know better than to write Portugal off by now, anyone anticipating a repeat of their Euro 2016 success will probably be disappointed. None of this summer's victorious squad will be involved in the team's first Olympic appearance since 2004, though seven of the selection that finished second in the 2015 UEFA U21 Championship travel to Brazil. They should qualify from a group whose other big threat is Argentina, a squad bolstered by West Ham's Manuel Lanzini, but Germany are possible quarterfinal opponents and will present a step too far.
MANAGER: Portugal will be coached by Rui Jorge, who guided that U21 team to last year's final in Sweden and has been at the helm since 2010. The former national team left-back has Olympic experience of his own, having played on the team that finished fourth at Atlanta '96.
STAR PLAYER: Skipper Bruno Fernandes had an impressive season in Serie A with Udinese last term and has been linked with a move to Torino. The attacking midfielder uses the ball perceptively and has an eye for goal; he is destined for bigger things and will need to be at his influential best if Portugal are to make inroads in Brazil.
OVERAGE STARS: When Portugal's wider wealth of talent is considered, none of the three overage names selected for Rio do much to stir the blood. Nacional winger Salvador Agra had a fine 2015-16 season domestically and has been linked with Leeds United, while former U21 captain Sergio Oliveira, now 24, is unlikely to have a future with parent club Porto. The third, Andre Martins, is the squad's most experienced member but is club-less since leaving Sporting. -- Nick Ames.
PREDICTION: Quarterfinals
ARGENTINA: Defeat in the final of the Copa Centenario set off a chain reaction. Lionel Messi (with others possibly following) announced his retirement from international football, which gave the Olympic tournament an extra urgency as a stepping stone for possible replacements. But with the local clubs reluctant to release players, coach Gerardo Martino resigned; at one point, the idea of not sending a team to Rio was floated.
MANAGER: Julio "el Vasco" Olarticoechea was a diminutive defender who won the World Cup with Argentina in 1986. He was in charge of Argentina's women's team when Martino resigned and as the only coach working with the Argentine FA, was hurriedly given the task of preparing a side for the Olympics.
STAR PLAYER: Angel Correa of Atletico Madrid is a little striker with skill and pace, versatility and intelligence. He can slip through passes like a playmaker, cross like a winger and finish with the aplomb of a centre-forward. Two years ago, he was out of the game for a few months when a routine medical exam detected a heart problem.
OVERAGE PLAYERS: Argentina have selected two, both in defensive positions where the national team has not recently enjoyed much strength in depth. Centre-back Victor Cuesta of Independiente, who went to the Copa Centenario, will captain the side, while the goalkeeper is Geronimo Rulli of Real Sociedad, who is being linked with a move to Manchester City. -- Tim Vickery
PREDICTION: Quarterfinals