The Gunners went into the game in sixth place on 13 points and were coming off the back disappointing 3-2 loss against Olympiakos in the UEFA Champions League.
Mesut Özil had come under fire from sections of the media for his recent performances but Arsene Wenger showed faith in the 26-year-old and started him against United.
The World Cup winner setup Alexis Sanchez with the opening goal on 6 minutes and got his name on the scoresheet just a minute later.
Özil opened his goal scoring account in the process and now has four assists for the Gunners this season.
Arsenal v Manchester United
Kick-Off: 16:00 GMT
Arsenal confirmed starting lineup: Cech, Bellerin, Mertesacker, Gabriel, Monreal, Coquelin, Cazorla, Ramsey, Ozil, Sanchez, Walcott
Subs: Ospina, Giroud, Campbell, Chamberlain, Gibbs, Debuchy
Manager: Arsene Wenger
Manchester United confirmed starting lineup: De Gea, Young, Smalling, Blind, Darmian, Carrick, Schweinsteiger, Mata, Rooney, Memphis, Martial
Subs: Romero, Jones, McNair, Schneiderlin, Valencia, Fellaini, Wilson
Manager: Louis van Gaal
Goals: 6′ Sanchez, 7′ Özil, 20′ Sanchez