Pierre-Emerick Aubameyang’s second-half penalty saw Arsenal claim their first win at Old Trafford since 2006.
A dominant first half ended goalless and Manchester United improved after the break but Paul Pogba brought down Héctor Bellerín midway through the second half and Aubameyang sent David de Gea the wrong way to end their hoodoo away in Manchester.
The Gunners had to withstand late pressure and Mohamed Elneny almost put through his own net but the defence remained resolute to secure a deserved three points.
Mikel Arteta raised a few eyebrows with his team selection with three changes from the defeat to Leicester City last weekend. Rob Holding returned from injury to replace David Luiz while Willian came into the front free but the most surprising inclusion saw Elneny preferred to both Granit Xhaka and Dani Ceballos in midfield alongside Partey.
His choice proved to be justified as the Egyptian was excellent alongside Partey, Bellerín, Gabriel Magalhães, Partey and Alexandre Lacazette as the Gunners ended their six-year wait for a win away at one of the Big Six.
Arsenal didn’t look like a side with such a torrid record at the stadium as they started confidently. The aggressive press was locking United into their defensive third and the ability to win the ball back quickly was keeping them there.
Partey was the dominant man in midfield with the hosts struggling to match his physicality and quick feet, as the Ghanaian kept Arsenal ticking in possession.
There was a slight bias towards the left-hand side but the first chance of the game came down the opposite flank when Aubameyang was just inches away from connecting to Bellerín’s low cross.
The pace of Marcus Rashford and Mason Greenwood was Manchester United’s best outlet and the duo combined for the hosts’ only chance of the half but Bernd Leno was equal to Greenwood’s effort.
Elneny and Partey ensured Arsenal remained on the front foot and the pressing of the front three, most notably Lacazette, was exceptional and almost led to the opener.
Willian, who was much improved, almost broke his duck for Arsenal after a neat one-two with Aubameyang but his curling shot clipped the crossbar.
Bellerín’s deliveries continued to cause problems with Bukayo Saka heading over when unmarked. The Spaniard also picked out Aubameyang and the captain found Lacazette but Victor Lindelöf got a vital toe to the ball to deny the Frenchman a close-range effort.
Manchester United changed their formation at the break and they saw more of the ball in the opening periods of the second half but it was the Gunners who should have opened the scoring when more harassing from Lacazette saw him steal the ball from Fred and set up Aubameyang but the striker slotted it the wrong side of the post.
The Red Devils showed their threat from a free kick with Harry Maguire stealing in at the back post but the defender headed wide.
But it was Arsenal who were turning the screw and minutes after Partey tested de Gea from range, the Gunners were handed a penalty. Pogba took down Bellerin and Mike Dean had no hesitation in pointing to the spot. Aubameyang stood over the ball and sent the goalkeeper the wrong way.
Gabriel, who rejected the chance to join United in the summer, was fortunate not to receive a second yellow for his challenge on Greenwood as United upped the ante.
Arteta’s first change saw Eddie Nketiah replace the excellent Lacazette but the striker didn’t see too much of the ball as United piled on late pressure and it almost paid off when Elneny diverted Donny van de Beek’s cross onto the face of Leno and then the post.
Ainsley Maitland-Niles and Shkodran Mustafi came on for the final few minutes to help Arsenal see out the game and claim a huge victory.