Arsenal seized the initiative in the race for the top four with a 2-0 victory over Manchester United that inflicted the first league defeat of Ole Gunnar Solskjaer's tenure.
Granit Xhaka forced an uncharacteristic goalkeeping error from David de Gea as his swerving shot fired the Gunners in ahead inside 12 minutes before Pierre-Emerick Aubameyang's penalty made sure of the victory midway through the second half.
United hit the woodwork twice in the first half but there was a clear hangover from Wednesday's Champions League heroics in Paris as they suffered their first Premier League defeat December 16.
United hit the woodwork twice in the first half but there was a clear hangover from Wednesday's Champions League heroics in Paris as they suffered their first Premier League defeat December 16.
Arsenal leapfrogs United into fourth as a result of their ninth-successive home victory and moves to within a point of third-place Tottenham as the top-four race intensifies with eight games to play.
Player ratings
Arsenal: Leno (7), Sokratis (6), Koscielny (6), Monreal (6), Maitland-Niles (6), Xhaka (7), Ramsey (8), Kolasinac (7), Ozil (6), Aubameyang (7), Lacazette (6).
Subs: Iwobi (6), Suarez (5), Nketiah (n/a).
Man Utd: De Gea (4), Young (5), Smalling (5), Lindelof (5), Shaw (6), Dalot (6), Matic (5), Fred (5), Pogba (6), Rashford (6), Lukaku (6).
Subs: Martial (5), Greenwood (5).
Man of the Match: Aaron Ramsey.
Arsenal had United under the cosh early on, registering three attempts, all of which were off target, inside the opening nine minutes, but United's first effort nearly yielded the opener.
Luke Shaw strode down the left flank and picked out Romelu Lukaku in the Arsenal area, but the Belgian could only divert the ball onto the crossbar before Paul Pogba's attempted rebound was blocked.
Arsenal then took a deserved lead, albeit in bizarre circumstances, as Xhaka swerving shot from 25 yards wrong-footed De Gea on its way into the middle of the United goal.
Despite seeing little of the ball, United almost drew themselves level on 19 minutes as Fred took aim from the edge of the area and beat the outstretched arm of Bernd Leno, only to see his effort clip the post.
Arsenal continued to pepper the United goal but lacked the killer touch, and they nearly paid the price on 36 minutes when Lukaku tried to round Leno, but the Arsenal goalkeeper made contact with the ball, forcing the striker to swipe at a shot which flashed across the face of goal.
Subs: Iwobi (6), Suarez (5), Nketiah (n/a).
Man Utd: De Gea (4), Young (5), Smalling (5), Lindelof (5), Shaw (6), Dalot (6), Matic (5), Fred (5), Pogba (6), Rashford (6), Lukaku (6).
Subs: Martial (5), Greenwood (5).
Man of the Match: Aaron Ramsey.
Arsenal had United under the cosh early on, registering three attempts, all of which were off target, inside the opening nine minutes, but United's first effort nearly yielded the opener.
Luke Shaw strode down the left flank and picked out Romelu Lukaku in the Arsenal area, but the Belgian could only divert the ball onto the crossbar before Paul Pogba's attempted rebound was blocked.
Arsenal then took a deserved lead, albeit in bizarre circumstances, as Xhaka swerving shot from 25 yards wrong-footed De Gea on its way into the middle of the United goal.
Despite seeing little of the ball, United almost drew themselves level on 19 minutes as Fred took aim from the edge of the area and beat the outstretched arm of Bernd Leno, only to see his effort clip the post.
Arsenal continued to pepper the United goal but lacked the killer touch, and they nearly paid the price on 36 minutes when Lukaku tried to round Leno, but the Arsenal goalkeeper made contact with the ball, forcing the striker to swipe at a shot which flashed across the face of goal.