Video Assistant Referee causes controversy every week in the Premier League, but how are decisions made, and are they correct?
After each weekend, we take a look at the major incidents to examine and explain the process in terms of VAR protocol and the Laws of the Game.
In this week's VAR Review: Was the VAR right to disallow Arsenal's late "winner" from Kai Havertz against Aston Villa? Should Brighton midfielder Carlos Baleba have been sent off against Manchester United? And why did Nottingham Forest have a goal ruled out for offside against Southampton?
Arsenal 2-2 Aston Villa
Possible handball: Havertz when scoring
What happened: With game tied at 2-2, Arsenal scored what they thought was a dramatic, 87th-minute winner at home to Aston Villa when Mikel Merino saw his shot deflect into the back of the net off Kai Havertz. Villa's Boubacar Kamara, who was right in line with Merino's shot, appealed for handball, and while the Arsenal players celebrated, it was looked at by the VAR, John Brooks.
VAR decision: Goal disallowed.
VAR review: At first this seemed to be a regular deflection off Havertz, wrong-footing Villa goalkeeper Emiliano Martínez to give Arsenal a dramatic winner. Yet it soon became clear there was doubt about the goal and the ball might have come off the Germany international's arm.
The two-tier handball law, which means a defender wouldn't concede a penalty in exactly the same scenario, does cause confusion. An attacker cannot score a goal if the ball touches his hand or arm, even if it's tucked into the body. Yet if comes off a defender in the same way, it can't be a spot kick because the player hasn't made their body unnaturally bigger.
The law for the attacker is very simple, though: you cannot score a goal with your arm, regardless of whether the touch is accidental or the ball touched another part of your body first. It's a binary part of the law and doesn't require any kind of interpretation (this is why the referee didn't need to go to the monitor.) If the ball hits an attacker's arm and goes into the goal, it's always a free kick to the defending team.
The VAR, who is able to sync multiple camera angles in one view, was looking for proof that the ball hit the arm. It was the main point of contention for Arsenal supporters, who felt it had deflected off Havertz's stomach or hip.
Verdict: The front view provides clear evidence that the ball came off Havertz's forearm. The way the ball shot upwards on the rear view also suggested a deflection off the arm, rather than it coming off the chest.
The VAR was looking for definitive proof and, while there might be some opposing views, it would have been very controversial not to intervene and rule out the goal.
Other clues were there, though. It's not something the VAR would consider, but the Arsenal celebrations were particularly muted for such a crucial goal. Merino, who had the perfect view, in particular showed little emotion, while the Gunners soon began running back toward the halfway line ,which gave the impression they thought the goal was going to be ruled out.
Man United 1-3 Brighton
Possible DOGSO red card: Baleba foul on Zirkzee
What happened: Manchester United were awarded a spot kick in the 20th minute when Joshua Zirkzee was hauled down inside the area by Carlos Baleba. Referee Peter Bankes produced a yellow card, and the VAR, Craig Pawson, checked both the penalty and a possible red card for denying an obvious goal-scoring opportunity (DOGSO). (watch here)
VAR decision: Penalty stands, scored by Bruno Fernandes; no red card.
VAR review: There was no doubt about the spot kick, with Baleba putting his arm around the neck of Zirkzee and pulling him to the ground.
The nature of Baleba's challenge means it wasn't covered by the double-jeopardy exemption, when a player is booked only as they have made a genuine attempt to challenge the opponent or the ball.
So whether this should be red or yellow card comes down to the quality of the scoring chance, and that's determined by what happens with the ball and where the opposition players are.
Just before Baleba committed the foul, Zirkzee opted to drag the ball back rather than take a shot -- this was crucial in the VAR opting not to recommend a review.
You can argue that it was still an obvious goal-scoring opportunity, and had Bankes sent Baleba off, it wouldn't have been overturned. But that change of direction from the Man United striker, taking the ball away from goal and giving goalkeeper Bart Verbruggen the possibility of challenging before Zirkzee could get a clear shot away, alters the picture for DOGSO.
Earlier this season, Brentford's Ethan Pinnock escaped a VAR red card when he pulled back Aston Villa's Ollie Watkins, who was directly through on goal with the ball in front of him. The Premier League's Key Match Incidents Panel ruled that Pinnock hadn't made a fair challenge and that it should have been a red card on the field but didn't reach the threshold for a VAR review.
Zirkzee's chance was of a lower quality as he wasn't continuing the forward momentum toward goal, so that would suggest Pawson was correct to uphold the yellow card.
Verdict: It's incredibly difficult to receive a DOGSO red card inside the penalty area these days, but this was the kind of challenge where it could apply. Baleba was fortunate because it was only the way Zirkzee shifted the ball that changed the DOGSO consideration and saved the Brighton player from a VAR intervention.
Possible foul: Van Hecke on Dalot before Pedro goal
What happened: João Pedro thought he had put Brighton & Hove Albion 2-1 up in the 53rd minute when he expertly turned inside the area and fired past André Onana. However, Manchester United's players appealed for a foul in the buildup, and it was checked by the VAR. (watch here)
VAR decision: Goal disallowed.
VAR review: Brighton had delivered a free kick into the Man United area, and as Diogo Dalot went to hook the ball, he was kicked by Jan Paul van Hecke.
We've seen a few situations like this crop up, with the key consideration for the VAR being whether one player had got to the ball first and had the right to be able to play it or it was a genuine coming together on a 50-50 (or, did the players kick each other?)
It has been more commonly seen in possibly penalty situations. Indeed, Pawson was the referee for Brighton's game at Aston Villa three weeks ago when the VAR (Stuart Attwell) advised a spot kick for Pedro's challenge on Morgan Rogers. That looked like a soft penalty, yet the Premier League's Key Match Incidents Panel unanimously voted that Attwell was right to send Pawson to the pitchside monitor.
This was a clearer case, however. Dalot had positioned himself to clear the ball, and Van Hecke kicked Dalot's foot onto the ball.
Verdict: This might have been more controversial had Brighton not gone on to win the game 3-1, but it was a correct VAR intervention. The Man United defender didn't get the chance to make his clearance because he was kicked by Van Hecke.
Nottingham Forest 3-2 Southampton
Possible offside: Wood on Milenkovic goal
What happened: Nottingham Forest scored what they thought was a fourth goal in the 64th minute through Nikola Milenkovic, who headed home from a free-kick routine. As the Forest players celebrated, the VAR, Graham Scott, checked a possible offside offence by Chris Wood. (watch here)
VAR decision: Goal disallowed.
VAR review: It's a unique and complication offside decision and one that will no doubt split opinion.
The only phase that mattered was the one created when Anthony Elanga took the free kick. At this point, Wood was clearly in an offside position, and, as he didn't actually touch the ball, his actions in relation to the Southampton defenders determined whether there was an offence.
When Milenkovic headed the ball, a new phase was created, and by this time Wood was onside, so there couldn't be any effect on goalkeeper Aaron Ramsdale.
As the ball was floated into the area by Elanga, Wood came into contact with Paul Onuachu, which could have affected the Southampton defender's decision about challenging Milenkovic. Having an influence from an offside position on a player who could challenge for the ball is always going to be looked at by the VAR -- though the VAR offside given against Everton's Orel Mangala last month was a clearer example with obvious blocking.
Wood also made an attempt to play the ball, but because he challenged his own player rather than an opponent this was out of the ordinary too. The controversy was around whether attempting to head a ball that was played by a teammate could have an influence on defenders who were seemingly not trying to get to the ball themselves. But would the defenders have made the same choice if Wood weren't there?
Verdict: As Wood was in contact with a Southampton player and made an attempt to play the ball, the VAR believed this had an influence on the phase.
Think of it this way: should an attacker be allowed to stand in an offside position, take the attention of a defender and then try to head the ball? Had Wood not jumped for the ball, he might have got away with it, but making a play created a clear potential offence.
Forest fans will be against it, and the decision looks a soft one, but there was always a high chance of VAR intervention.
Referee Anthony Taylor had to go to the monitor as it was a subjective offside, which applies whenever the offending player has not touched the ball.
Brentford 0-2 Liverpool
Possible penalty: Handball by Konaté
What happened: Sepp van den Berg attempted to help the ball into the centre of the penalty area in the 60th minute, but it hit the arm of Ibrahima Konaté. Van den Berg and other Brentford players appealed for a penalty, but referee Andy Madley was adamant there was no offence. It was checked by the VAR, Paul Tierney.
VAR decision: No penalty.
VAR review: The ball hit Konate from close proximity, with his arm down by his side.
There was nothing Konate could have done to avoid the ball, while his arm wasn't in an unexpected position for his movement and wasn't making his body bigger.
Verdict: All three VAR penalties awarded this season (Matty Cash, Tyler Adams, Matthijs de Ligt) have seen the defender with their arm fully extended away from the body. There should be no expectation of a penalty in this situation.
Possible penalty: Challenge by Flekken on Díaz
What happened: Luis Díaz latched onto a pass from Ryan Gravenberch but saw his shot saved by Mark Flekken. The Brentford goalkeeper failed to hold the shot but got back up to stop the ball going out for a corner. Díaz reacted to try to get to the loose ball, but the Liverpool attacker went to ground as Flekken moved toward it again. Díaz appealed for a penalty, but again referee Madley wasn't interested. (watch here)
VAR decision: No penalty.
VAR review: This would have been an interesting VAR decision had the referee given the penalty, because although Díaz appeared to go down very easily, there was contact with his right foot on the left arm of Flekken.
The goalkeeper, however, actually pulled out of the challenge and made no attempt to get a glove to the ball the second time. That didn't mean the goalkeeper cannot make a foul, but it was less likely to be judged as one.
Verdict: There was not enough in this for the VAR to intervene, but with the way protocol works, with evidence of contact by the goalkeeper on the Colombia international, it was unlikely to have been overturned if awarded by Madley.
Díaz got only a very small touch on the ball, suggesting he was playing for contact rather than possession.
Newcastle 1-4 Bournemouth
Possible ball out of play on Ouattara goal
What happened: Dango Ouattara scored a third goal for AFC Bournemouth in the 61st minute when he fired into the net after a goal-mouth scramble. As the players celebrated, Newcastle United's players protested that the ball had already gone out of play. It was checked by the VAR, Peter Bankes. (watch )
VAR decision: Goal disallowed.
VAR review: Unlike some of the more marginal ball-out-of-play situations we've seen in recent times, this was a straightforward decision.
Verdict: A very easy one for the VAR as the ball was in view on the goal-line camera -- which wasn't the case for Newcastle's controversial goal against Arsenal last season.
Play didn't restart with the goalkeeper but rather at the point the incident happened. As the ball came off a Newcastle player last, it was a corner to Bournemouth.
Everton 3-2 Tottenham
Possible penalty: Branthwaite challenge on Son
What happened: Son Heung-Min had possession inside the Everton penalty area in the 27th minute and looked to work the ball back around the box. He went to ground under pressure from behind by Jarrad Branthwaite, but referee Darren England wasn't interested in penalty appeals.
VAR decision: No penalty.
VAR review: If this had been given as a penalty by the referee, it wouldn't have been overturned.
But there's too much doubt for a VAR review, specifically around whether Son had slowed his forward momentum to cause Branthwaite to go into the back of him.
Verdict: Without more of a clear challenge from the defender to cause the Tottenham Hotspur player to go down, the VAR, John Brooks, wasn't going to get involved.
Some factual parts of this article include information provided by the Premier League and PGMOL.