Granit Xhaka’s early strike and Pierre Emerick-Aubameyang’s penalty 21 minutes from time moved the Gunners into fourth, two points above United in fifth.
Arsenal struck a potentially significant blow in the race for the Premier League top four with a 2-0 win over Manchester United at Emirates Stadium on Sunday.
A Granit Xhaka strike and a second-half penalty from Pierre-Emerick Aubameyang, who missed from the spot in the 1-1 draw with Tottenham last week, gave the Gunners three valuable points that lift them into fourth.
The result also ends United’s nine-game winning run away from home under Ole Gunnar Solskjaer, just four days on from their dramatic Champions League victory over Paris Saint-Germain.
Arsenal started positively but should have been behind nine minutes in, when Romelu Lukaku steered Luke Shaw’s low cross against the crossbar from six yards out.
The Gunners punished that miss three minutes later, when Xhaka’s swerving strike from 25 yards out completely bamboozled David de Gea and nestled into the left-hand corner.
Fred struck the base of the post as United sought a quick response, and both Marcus Rashford and Lukaku should have done better after finding space inside the penalty area.
Lukaku was denied by a good Bernd Leno save when Rashford picked him out with a clever pass, and the German was out again to smother the ball at the feet of the England striker as United’s pressure grew.
Arsenal made the most of those missed opportunities 21 minutes from time, when Aubameyang sent De Gea the wrong way from the penalty spot after Alexandre Lacazette went to ground under minimal contact from Fred.
What does it mean? Advantage Arsenal in the top-four chase
The Gunners have now moved two points above United into fourth place, just one behind Tottenham in third, with only eight matches left to play.
With Chelsea drawing at home to Wolves earlier, Unai Emery’s men now have the edge in a race for the Champions League spots that is getting seriously interesting.
For United, their winning run under Solskjaer ends in a game where, for once, he seemed to hinder his side with his selection.
Leno outshines De Gea
Leno made three good saves and a couple of timely interceptions just when United’s pressure was building. For once, De Gea was outshone at the Emirates.
Solskjaer, at last, gets it wrong
Starting with Pogba wide left made him ineffective early on, and by the time Solskjaer switched up the system, United were chasing the game.
Arsenal face Rennes on Thursday in their last match before the international break. United meet Wolves in next Saturday’s FA Cup quarter-final.