Pierre-Emerick Aubameyang rolled home a nerveless second-half penalty as Arsenal struck a huge blow in the race for the top four.
Granit Xhaka had put us ahead with a long-range goal in the opening half, but after a dangerous United side repeatedly threatened to draw level, Aubameyang exorcised the demons of his penalty miss last weekend to seal a huge three points.
It was just reward for a hard-working, battling performance.
We started like a side determined to put Thursday's poor result behind us, and soon started to rack up the shot count in the opening half.
The twin strike-force of Aubameyang and Alexandre Lacazette started well, both trying speculative shots in the opening 10 minutes, but it was the visitors who came closest to breaking the deadlock when Romelu Lukaku hit the crossbar from close range. It was certainly a let off and we took full advantage shortly afterwards.
Alexandre Lacazette rolled the ball to Xhaka some 25 yards from goal - the midfielder steadied himself before swerving his shot past a wrong-footed David de Gea. At first glance it appeared as though the shot must have taken a deflection, but it was simply the movement on the ball that had deceived the keeper.
The half continued to be an open affair, Lacazette had a chance charged down in the area before United struck the woodwork again, this time Fred hitting the foot of the post.
Bernd Leno made a good save to deny Lukaku from close range as United continued to threaten.
But we were also looking dangerous when breaking - Sead Kolasinac found plenty of room on the left flank, but was caught offside twice when he looked to be free of the last man.
United were certainly growing as an attacking force, and for the second weekend in a row Leno came up with a big save at an important moment.
Shortly after the interval he came quickly off his line to save from Lukaku at point blank range. It came just moments after Laurent Koscielny made a superb diving block in the penalty area. It was all hands to the pump. Questions were being asked of our defence, and they stood firm.
Then came the second to settle our nerves. Lacazette was bundled over in the box and referee Jon Moss pointed to the spot.
Up stepped Aubameyang. The man who's penalty miss was so costly last Saturday took the responsibility on his shoulders in front of the North Bank crowd.
This time there was no mistake from 12 yards. He rolled the ball calmly down the middle of the goal as David de Gea dived to his left. Cue wild celebrations.
It was his 20th goal of the season and the relief was palpable.
The rain started to lash down at the Emirates, but it couldn't dampen the home fans' spirits, or indeed extinguish the intensity levels the side had displayed all afternoon.
HOW IT HAPPENED
Unai named a very attacking side, with both Pierre-Emerick Aubameyang and Alexandre Lacazette starting ahead of Mesut Ozil.
Henrikh Mkhitaryan missed out against his old team though, with a slight back injury.
WHAT IT MEANS
With Tottenham losing on Saturday, and Chelsea drawing at home to Wolves earlier on Sunday, we have risen to fourth place in the Premier League – just one point behind Spurs.
We switch our attention back to the Europa League, to take on Rennes on Thursday. And for the second round in a row we will need to win by at least two goals at Emirates Stadium to progress to the next round. The match kicks off at 8pm, and is our last game until we host Newcastle in the Premier League two and a half weeks later.
There are now eight games remaining in the Premier League season and the race for the top four is heating up.
Here are the remaining Premier League fixtures for the sides in the hunt for the top four places…
April 1 – Newcastle (H)
April 7 – Everton (A)
April 15 – Watford (A)
April 20 – Crystal Palace (H)
April 29 – Leicester City (A)
May 4 – Brighton & HA (H)
May 12 – Burnley (A)
TBA – Wolves (A)
March 17 - Everton (A)
March 31 – Cardiff City (A)
April 8 – West Ham (H)
April 14 – Liverpool (A)
April 22 – Burnley (H)
April 28 – Manchester United (A)
May 4 – Watford (H)
May 12 – Leicester City (A)
TBA – Brighton & HA (H)
March 30 – Watford (H)
April 2 – Wolves (A)
April 13 – West Ham United (H)
April 21 – Everton (A)
April 24 – Manchester City (H)
April 28 – Chelsea (H)
May 4 – Huddersfield Town (A)
May 12 – Cardiff City (H)
March 31 – Liverpool (A)
April 7 – Brighton & HA (H)
April 13 – Huddersfield Town (H)
April 20 – Manchester City (A)
April 27 – West Ham United (H)
May 4 – Bournemouth (A)
May 12 – Everton (H)
TBA – Crystal Palace (H)
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