At the end of Howard Webb's toughest weekend since taking up his new role as chief refereeing officer in the Premier League, former official Dermot Gallagher gives his verdict on the big decisions.
Manchester United 2-1 Manchester City
INCIDENT: VAR check cleared Marcus Rashford from being offside in the build-up to Bruno Fernandes' equaliser (78) - to the fury of City's players, who protested that the forward had interfered with play.
A Casemiro pass through for Rashford appeared to find the forward in a clear offside position but he didn't touch the ball, despite it being right by his feet, and Fernandes stepped in to curl home from the edge of the box. City were incensed but VAR judged Rashford hadn't touched the ball or impacted the City defence to be offside.
TIME TAKEN BY VAR: 60 seconds
What is the offside rule in this case?
A player in an offside position at the moment the ball is played or touched by a team-mate is only penalised on becoming involved in active play by:
DERMOT'S VERDICT: Wrong decision, offside.
DERMOT SAYS: "As a referee I would have given offside.
"But it's difficult as it is a subjective decision. Different people have interpreted it differently. For me personally, I think the safest decision is offside.
"I think that for a number of reasons. Firstly, I think Rashford is too close to the ball.
"I think he impacts on the goalkeeper and he impacts on Akanji's run. I think he changes his running position. Originally, when he sees the ball he starts moving to the right, and then he goes to the left - towards the ball.
"The assistant referee Darren Cann then makes the decision. He ran the line in the World Cup final so I think he'd know more about offside than me, so I'd take his view of blowing the whistle.
"If you look at the angle from behind the goal, you can see the referee's view, which is why the law becomes so complex.
"The referee can see the distance between Akanji and Rashford and he feels in his mind that the defender is not going to get there.
"The law is clear on whether Rashford touches the ball as he doesn't. Does he impact on Ederson? Has Ederson got to think who is going to shoot?
"Stuart Attwell has made the decision that it doesn't impact on Ederson's thinking. He's gone to Darren Cann and spoken about it.
"If Darren Cann interprets it one way and Stuart Attwell interprets it another, the vote is 1-1.
"If the vote is 1-1, the referee is always going to back himself and he's decided with the law as it is, he can award the goal."
Pep: Rashford was offside for Man Utd's first goal | 'He intervenes'
Man City boss Pep Guardiola said: "Manu Akanji stops the line [of running]. If he knows that he is going to go with Rashford, he will go back with him and do the duel one versus one and he sees what happens. But he intervenes in the action.
"The referee decided he did not want to intervene in this stadium. It's OK, what are we going to do? Are we going to make a complaint? No. Congratulations for that. Sometimes it happens in our [favour]. Sometimes [it's like] that. The decision is they didn't believe he [impacted the play]. Rashford was intervening in this action when this happened.
"It's Old Trafford. We have to play much better. Like it's Anfield. We have to do better.
"The rule is the rule, the interpretation belongs to the referee. I say Rashford is offside, Bruno is not. The situation is for the referees.
"When one player shoots and [another] player is in front of the keeper and does not touch the ball, it's disallowed all the time. The decision is of course [belonging to] the referees and VAR. We follow the action, we don't make an offside [appeal], we follow the action and after the action, it's either Ederson intervenes [with a save] or not.
"What can we improve? After we concede the goal, in the next few minutes we cannot concede the next one. We allowed them to score. Come, come, come. This is the most important detail we have to improve for the future."