MELBOURNE, Australia -- Novak Djokovic opened his quest for a record seventh Australian Open title and his 15th Grand Slam singles championship with a 6-3, 6-2, 6-2 win over American qualifier Mitchell Krueger on Day 2 of the Australian Open on Tuesday.
Djokovic opened the night program at Rod Laver Arena with a worry-free win, breaking his opponent in the fifth game of the third set to help ensure he'd finish the match in a tidy 2 hours, 3 minutes.
Krueger was part of a rough day for American men, who went 1-5 Tuesday; Ryan Harrison had the lone victory.
It wasn't so easy earlier Tuesday for No. 8 seed Kei Nishikori, who rallied from two sets down and won 10 straight games before Kamil Majchrzak retired with the score at 3-6, 6-7 (6), 6-0, 6-2, 3-0.
Nishikori had a chance to win the second set, up 30-0 on the Polish player's serve at 5-4, but he let Majchrzak back into the game. When the set went to a tiebreaker, two unforced errors by Nishikori handed his opponent the set.
Those mistakes riled Nishikori between the second and third sets, and he was obviously upset with himself as he placed ice cubes in a plastic bag that he applied to the back of his neck.
He came out firing to start the third set, went on his 10-game streak and rattled off 15 of the last 17 games before Majchrzak had enough and stopped the match due to cramping.
Also on Day 2, fourth-seeded Alexander Zverev broke Aljaz Bedene's serve in the seventh game of the third set and went on to complete a 6-4, 6-1, 6-4 win over the Slovenian player to reach the second round.
Stan Wawrinka won his first-round match over Ernests Gulbis when the Latvian player had to retire at 3-6, 3-1 because of a back injury. Gulbis received treatment on his back earlier in the match.
Wawrinka won the Australian Open in 2014 for his first Grand Slam title and has now reached the second round in each of his appearances at Melbourne Park. He next plays Milos Raonic, who hit 30 aces and never faced a break point to beat local hope Nick Kyrgios 6-4, 7-6 (5), 6-4 in their first-round match.
Among the other men advancing were No. 11 Borna Coric, No. 12 Fabio Fognini, No. 15 Daniil Medvedev and No. 25 Denis Shapovalov, Pierre-Hugues Herbert also beat Sam Querrey 5-7, 7-6 (6), 6-3, 6-1.
Also on Tuesday, a day after the new 10-point tiebreaker was used to decide a match in women's singles at the Australian Open, the men had their first decided in the same way.
Jeremy Chardy beat fellow Frenchman Ugo Humbert 3-6, 7-6 (6), 6-4, 6-7 (4), 7-6 (6), with Chardy advancing when he was the first player to reach 10 points in the fifth-set tiebreaker.
On Monday, Katie Boulter had the distinction of winning in the first-ever 10-point tiebreaker in her match against Ekaterina Makarova.
Seventh-seeded Dominic Thiem held off Benoit Paire 6-4, 6-3, 5-7, 1-6, 6-3 in a first-round match that finished after 2 a.m. on Wednesday.
Thiem will next play Australian wild-card entry Alexei Popyrin, who beat Mischa Zverev 7-5, 7-6 (7), 6-4 earlier on Day 2.
Information from The Associated Press was used in this report.