Arsenal stunned Manchester United with three goals in the opening 20 minutes as the Gunners moved up to second in the Premier League table. United had no answer to Arsenal's opening burst as Alexis Sanchez and Mesut Ozil scored twice in 74 seconds. Sanchez added a third from 18 yards as the Gunners beat United for just the second time in 14 league meetings. United improved after the break but Arsenal substitute Alex Oxlade-Chamberlain hit the crossbar late on. Defeat leaves Louis van Gaal's side in third place, behind Arsenal on goal difference.