There could have been few clearer penalty claims and Dean was standing near enough to make the perfect decision. Inexplicably, he chose to say no.
At that point, there seemed to be only one winner. How wrong those doubters were as Ferguson's team surged back, Giggs the architect behind the comeback just as Arshavin had sparked Arsenal earlier.
The difference was Dean said yes when United claimed their penalty as Rooney went crashing to the ground after Giggs had supplied the pass that sent him through one-on-on with Almunia.
Man of the match: Tough call but Wayne Rooney looked a clas act throughout, setting up plenty of attacks and creating the penalty for United's opening goal.
Moment of the match: Fletcher took out Arshavin inside the United penalty area, handled the ball in the tackle and was waved on. Arsenal fans should have known that things weren't going their way right there.
Attempt of the match: Van Persie hit the crossbar from a free-kick with Foster well beaten. Could have changed the complexion of the game.
Save of the match: Almunia's save from Nani in the dying moments was superb.
Talking point: Are United guaranteed a penalty at Old Trafford? Should they start games there 1-0?
Goal of the game: Arshavin scored an absolute beauty. A superstar in the making.