After a Kieran Gibbs own goal, and a Wayne Rooney strike, Olivier Giroud pulled one back for the Gunners but it was not enough.
Arsenal boss Arsene Wenger is now under increasing pressure but that is not something Manchester United fans or their manager Louis van Gaal are interested in given they have found their way back into the Champions League places and secured three points in a massive game.
With that in mind, we have put our heads together and come up with five things we learnt from Louis van Gaal and his men this weekend.
Click on the man who cannot beat United to see what we learnt.
Manchester United fans. What did you learn from your win at the Emirates? Let us know your thoughts below or tweet us @LaFootyettes.