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 both in terms of VAR protocol and the Laws of the Game.
In this week's VAR Review: Was it the correct decision to send off Liverpool midfielder Alexis Mac Allister? Did Dominik Szoboszlai deserve a penalty? And should Tottenham Hotspur defender Cristian Romero have been penalised for handball against Manchester United?
Possible red card overturn: Mac Allister on Christie
What happened: It was in the 58th minute, with Liverpool leading 2-1, when Alexis Mac Allister challenged Ryan Christie for a loose bouncing ball. The AFC Bournemouth player got there first, with Mac Allister catching him with his studs. Referee Thomas Bramall produced the red card, to the surprise of the midfielder.
VAR decision: Red card stands.
VAR review: The Premier League has a more liberal approach to tackling compared to the other major leagues, and that's shown in the number of red cards. Last season in England's top flight there were 17; contrast that with the 89 shown in LaLiga, 65 in Ligue 1 , 41 in Serie A and, from fewer matches, 20 in the Bundesliga.
More consideration is given to the level of force, rather than point of contact. Based upon that, we shouldn't be seeing a red card for a tackle like Mac Allister's; even Bournemouth boss Andoni Iraola agreed with his opposite number, Jurgen Klopp, that the midfielder shouldn't have been dismissed.
Christie is trying to clear the ball with a sidefoot action, while the Argentina international goes in with his studs leading and makes contact on the shin. Bramall has a good position and has deemed that Mac Allister has endangered the safety of an opponent due to the way he went into the challenge.
For the VAR, Paul Tierney, this is a difficult judgement. If the referee is saying the red card has been shown due to Mac Allister leading with his studs, can that be said to be a clear and obvious error?
Supporters generally hate the phrase "clear and obvious," and it's difficult to define. Fans say they just want the right decision to be made, but in a sport that is ruled by subjective decision-making that's essentially what "clear and obvious" means. The decision has to be clearly wrong, and if it's clearly wrong the VAR intervenes to make the right decision. But there will also have to be that subjective judgement of the VAR around that threshold.
Referees' chief Howard Webb is eager for his officials to be more decisive on the pitch, and not use VAR as a safety net. With the on-field call carrying the weight with VAR protocol, that does rely on good decision-making in tandem with "clear and obvious." It's always going to be a fine line between what happens on the pitch, a desire not to re-referee the game and the perception that VAR is achieving what it's supposed to.
Bramall is a recent addition to the Premier League taking charge of only his ninth game, and his first involving a Big Six club. Despite that he certainly isn't without confidence as one of only four referees to reject a VAR overturn at the monitor last season
Klopp will appeal to the Football Association and hope to avoid the three-game ban that would see Mac Allister miss matches against Newcastle United, Aston Villa and Wolverhampton Wanderers. There's a chance it could be successful, but it's by no means certain. As Mac Allister went into the challenge with a studs-first blocking motion, rather than an attempt to kick the ball, the independent panel which sits to judge appeals may feel that, in law, the red card wasn't an incorrect decision.
This shouldn't be held up as a benchmark, but seen as the outlier it is. It didn't take long for similar situations to arise which saw yellow cards; these tackles are the precedent, not Mac Allister.
In Manchester City's game against Newcastle, Rúben Dias was caught on the back of his calf by Anthony Gordon. It was a poor challenge, but without any force, and the England under-21 international was booked.
Another Newcastle player, Bruno Guimarães, then caught Phil Foden on the shin, in a similar place to Mac Allister. Again, the referee showed a yellow -- consistent with what we'd expect in the Premier League when there is no excessive force.
Possible penalty overturn: Rothwell foul on Szoboszlai
What happened: Liverpool were handed the chance to equalise in the 35th minute when Dominik Szoboszlai went to ground under a challenge from Joe Rothwell. Referee Bramall pointed to the spot, but did the Liverpool player exaggerate the nature of the contact?
VAR review: As with Mac Allister, this comes down to the power of the decision on the field and how VAR protocol is applied. While the over-riding ethos behind challenges in the penalty area is that contact must have a consequence -- the player should go down in the manner that fits the challenge -- that is overridden by lower-body challenges when the referee has given the spot kick.
Rothwell makes contact with Szoboszlai's leg, and shifts it across. The Hungary international theatrically throws himself into the air to exaggerate the level of contact and win the penalty -- and Bramall points to the spot.
Once the VAR has identified that contact, there's little place for him to go. It cannot be seen as a clear and obvious error to give a penalty, despite Szoboszlai's reaction. If the referee hadn't pointed to the spot, it's highly unlikely the VAR would have intervened, having taken Szoboszlai's reaction into account.
Last week, the VAR intervened to give a penalty to Brentford when Son Heung-Min tripped Mathias Jensen, who went down in an exaggerated fashion. The Independent Key Match Incidents Panel said that was right on the borderline of a VAR intervention, but a correct decision nonetheless.
Likewise, Brighton & Hove Albion were awarded a penalty when João Pedro went to ground under a challenge from Tom Lockyer and the referee awarded a spot kick. The panel judged the better decision in that incident to be no penalty, but also felt it wasn't a clear and obvious error for the VAR to intervene -- and it may well be the case with Szoboszlai.
Possible red card: Foul by Alisson on Anthony
What happened: Alisson came out of his area in the eighth minute and challenged Jaidon Anthony for the ball, bringing down the forward. The referee gave the free kick and booked the Liverpool goalkeeper, but was there a case for a red card?
VAR decision: No red card.
VAR review: The role of Ibrahima Konaté as a covering defender is crucial, meaning there cannot be an obvious goal-scoring opportunity for Anthony. There's the chance that the Bournemouth player could have got to the ball first for a shot on goal, but the officials couldn't be certain this would be the case -- so a booking rather than a red card isn't an incorrect decision.
Possible onside: Anthony on disallowed goal
What happened: Bournemouth thought they had taken the lead in the first minute when Anthony skipped through and fired past Alisson, but the assistant's flag went up for offside. However, Trent Alexander-Arnold played the ball before it reached Anthony, so should the goal have stood?
VAR decision: No goal.
VAR review: Last season, Liverpool were furious when they had a goal disallowed against Aston Villa when Ezri Konsa was adjudged not to have made a "deliberate play." This time they were the beneficiaries of this area of the law.
Anthony was offside when Marcos Senesi played the ball forward, but when Alexander-Arnold knocked the ball on he did so with a stretched motion in an attempt to play a high ball. The defender has no control over the outcome of his action, so it cannot be considered a "deliberate play" and the offside phase isn't reset.
It's not the last time we'll be visiting "deliberate play" this season.
Possible penalty: Handball by Romero
What happened: Alejandro Garnacho had a shot from outside the area in the 27th minute, with the ball hitting the arm of Cristian Romero. Manchester United were adamant they should have been awarded a penalty, but referee Michael Oliver wasn't interested.
VAR decision: No penalty.
VAR review: This would have most likely have been a penalty in any other major league but, as with red cards, the Premier League takes a much more lenient approach. Last season in the Premier League there were 24 spot kicks awarded for handball, compared to 43 in LaLiga, 33 in Ligue 1, 31 in Serie A and, from fewer fixtures, 27 in the Bundesliga.
Oliver judged that Romero was too close to the shot from Garnacho and, subjectively, the VAR said it was not a mistake. While proximity was a consideration, Romero had his right arm raised and if the penalty had been awarded it certainly wouldn't have been rescinded.
It was a borderline call, and we will likely see similar situations that result in a penalty. The handball law is complex, and each case has to be taken on its merits.
Handball is probably the area where fans feel there is the most inconsistency, but the law is so subjective that it will always be difficult to achieve perceived consistency.
Possible penalty: Martínez challenge on Romero
What happened: Romero looked to collect the ball inside the area when he went to ground under a challenge from Lisandro Martínez in the 54th minute. Referee Oliver said no to the appeals for a penalty and signalled for play to continue.
VAR decision: No penalty.
VAR review: We will see many similar incidents in the Premier League this season, when two players get to the ball at the around same time and the referee decides no foul has taken place.
It's one of those situations when outside the area the referee is likely to give a decision to one of the players, but inside the box he may feel there isn't enough to warrant a penalty.
Possible penalty overturn: Pickford challenge on Watkins
What happened: Aston Villa were awarded a penalty in the 24th minute when Ollie Watkins was caught by Jordan Pickford after the striker had attempted to get a shot on goal. Referee Anthony Taylor pointed to the spot.
VAR decision: Penalty stands, scored by Douglas Luiz.
VAR review: Just two weeks into the season and we have a few examples of goalkeepers challenging attackers and the different ways they are judged -- rightly or wrongly.
The difference with the Pickford challenge is the careless way he came for the ball. It wasn't just a keeper spreading himself for the shot, Pickford came out and made a wild swipe for the ball and then took the striker.
It's always going to be a judgement call on when a goalkeeper, or in fact a defender, crosses the line from an attempted block or save to a foul challenge, but few would argue against this spot kick.
It comes, of course, just a few days after the failure to award a penalty against Manchester United goalkeeper André Onana vs. Wolverhampton Wanderers. That led PGMOL to stand down three officials -- the referee, VAR and assistant VAR -- from duty this weekend. The incorrect Onana decision doesn't create the precedent for the season; both Onana and Pickford made challenges which were worthy of penalties.
Possible penalty: Areola challenge on Jackson
What happened: It was the ninth minute when Enzo Fernández tried to feed Nicolas Jackson through the centre. The striker burst into the area and was brought down by goalkeeper Alphonse Areola. Any claims for a penalty were quickly ended by the offside flag.
VAR decision: No penalty.
VAR review: A correct offside decision was made by the assistant, but this situation is notable for the way it was handled by referee John Brooks.
When Jackson was fouled, Brooks looked over to his assistant and the offside flag was raised.
However, rather than giving the offside first, Brooks blew and pointed to the penalty spot before immediately cancelling it and giving the offside.
Why is this important? As always, it's about the weight of the on-field decision. By making the call to give the spot kick, Brooks has given the indication to the players, supporters and the VAR what his decision would be if the review finds that Jackson was actually onside.
Without this, if Jackson is onside there is less likelihood of a penalty being awarded -- as the VAR would have to find a clear and obvious error in that original decision.
Possible encroachment: Soucek after Fernández penalty miss
VAR decision: No retake.
VAR review: Soucek has his foot on the line of the penalty area when Fernández struck the shot, which on a technical level means he was encroaching before clearing the ball.
However, protocol sets a limit on when the VAR should get involved, in order to limit the influence on penalties.
The VAR has to judge if the encroaching player has a material impact on the outcome of the kick, and that means he must prevent an opposition player from being able to play the ball.
It's the same logic that's applied to goalkeepers: if they are off their line but the kicker misses the target, or hits the woodwork, there should be no retake as the movement has not changed the outcome.
Soucek doesn't have a Chelsea player close to him when he plays the ball, so the VAR, Paul Tierney, was correct not to intervene.
Information provided by the Premier League and PGMOL was used in this story.