Striker Eddie Nketiah scored a last-minute winner to give Arsenal a 3-2
The striker scored a left-foot volley in the 90th minute to decide an edge-of-the-seat game that Arsenal deserved to win, although it also highlighted Manchester United's continued improvement under Erik ten Hag.
Marcos Rashford's hot streak continued in the 17th minute when he put United ahead, but Nketiah's first goal of the match quickly leveled the scores seven minutes later.
Bukayo Saka put Arsenal ahead in the 53rd minute, only for Lisandro Martinez's diving header six minutes later to leave things all square.
Arsenal did most of the pressing from them on, but it wasn't until the last minute of normal time that Nketiah's second goal of the match assured the points.
Earlier in the day, Erling Haaland's fourth hat-trick of the season saw Manchester City to a 3-0 win at home to Wolverhampton Wanderers.
He opened the scoring in the 40th minute with a powerful header from Kevin de Bruyne's cross and netted his second from the penalty spot four minutes after the break.
The Norwegian then scored his 25th league goal of the campaign after good work from Riyad Mahrez to round off the afternoon.
Leeds United controlled their match at home to Brentford and never looked in danger of losing as Brentford failed to have a shot on target, but despite five shots on target, they failed to really test Brentford keeper David Raya.
On Saturday, Liverpool and Chelsea played out a disappointing 0-0 draw at Anfield, which served to highlight the problems the two sides are facing.
Chelsea had an early goal from Kai Havertz ruled out for offside, and the best news for coach Graham Potter was an impressive cameo from new signing Mykhailo Mudryk.
Without Bruno Guimaraes, Newcastle were held to a 0-0 draw by Crystal Palace, whose goalkeeper Vicente Guaita made seven saves to deny Eddie Howe's side a goal.
Leicester City ended a four-game losing streak but will have been disappointed after Even Ferguson's 88th-minute goal earned Brighton a 2-2 draw.
Brighton had taken a 27th-minute lead through Kaoru Mitoma, but Leicester hit back with goals from Mark Albrighton in the 38th minute and a 63rd-minute effort from Hervey Barnes.
Jarrod Bowen scored twice to end West Ham's seven-game winless run with a 2-0 win at home to fellow strugglers Everton, who remain second from bottom and with coach Frank Lampard more questioned than ever.
Ollie Watkins' 77th-minute header gave Aston Villa a 1-0 win away to Southampton, who remain bottom of the table. The home side thought they had taken the lead through James Ward Prowse's deflected effort, but it was ruled out by the VAR.
Sam Sturridge's 83rd-minute goal denied former club Bournemouth a win at home to Nottingham Forest. Jaidon Anthony had given Bournemouth a 28th-minute lead, but Sturridge's goal leaves Bournemouth in the bottom three.