|1||Van der Sar|
Aaron Ramsey, who chose to join the North Londoners ahead of the Reds, scored the only goal of the game to inflict a fourth defeat of the Barclays Premier League campaign on the leaders.
Substitute Michael Owen was denied a late penalty when being brought down inside the box with a couple of minutes remaining after Nemanja Vidic appeared to escape conceding a spot-kick for a handball in the first half. But the Reds were not at their best and rarely replicated the sort of form displayed against Schalke in midweek.
Sir Alex Ferguson opted for Fabio at right-back and Nani in preference to Antonio Valencia with Anderson drafted into the midfield while the Gunners were without Cesc Fabregas, who injured a thigh in training.
Even without their captain, the hosts started brightly in the sunshine and dominated early possession - although Edwin van der Sar wasn't called into action.
Jack Wilshere lashed a great opportunity wide after a rare slip by Vidic, who cleared straight to the young Englishman, but the Reds' skipper was at his best to pressure Theo Walcott into firing a Robin van Persie cross over the bar soon afterwards.
Patrice Evra was on the top of his game to stretch to divert a van Persie centre away from Walcott and it took some time for United to fashion a threatening move. When it came, Fabio burst onto a Nani pass and stayed on his feet despite a risky challenge inside the box, only to be unable to pick out