What you need to know:
- Arsenal regrouped and Saka hit the post in a near repeat of his goal as De Gea watched nervously.
- De Gea made a fine save when Nketiah blasted at him from close range as the clock ticked down, with United unable to control the ball for sustained spells.
- United were close to holding out for the draw but Arsenal took all three points when Nketiah scored his second of the afternoon as a lengthy VAR check ruled him onside.
London, United Kingdom
Arsenal made a huge statement of their Premier League intent on Sunday, coming from behind to beat in-form Manchester United 3-2 in front of a raucous Emirates crowd.
United forward Marcus Rashford silenced the home fans with the opening goal but an equaliser from Eddie Nketiah and a wonderful second-half strike from Bukayo Saka turned the match on its head.
But the visitors, dangerous on the break throughout the match, levelled the pulsating encounter when Argentine defender Lisandro Martinez headed in after Arsenal failed to clear a corner.
The Gunners poured forward in search of a winner and eventually got the goal they deserved when Nketiah turned the ball home in the 90th minute.
Earlier, defending champions Manchester City had closed the gap to just two points with their 3-0 win against Wolves, courtesy of Erling Haaland's fourth hat-trick of the season.
Scott McTominay replaced Brazilian midfielder Casemiro, who was ineligible after picking up a fifth booking of the season in United's midweek draw with Crystal Palace, with loan signing Wout Weghorst again leading the line.
New Arsenal arrival Leandro Trossard, who joined late last week from Brighton, had to settle for a place on the bench as Mikel Arteta named an unchanged team.
There is growing sense of belief at the Emirates that the Gunners can at last end their long wait for the Premier League title, which they have not won since 2004.
Arsenal flew out of the blocks, with Thomas Partey flashing just wide as they surged forward.
But it was United who broke the deadlock in the 17th minute in stunning style, when Bruno Fernandes found Rashford, who skipped past Partey with ease and powered a low drive into the corner of the net from 25 yards.
Arsenal were level just seven minutes later when in-form Nketiah lost Aaron Wan-Bissaka at the back post to nod home Granit Xhaka's cross.
Now the wind was in the home team's sails as they poured forward but United went close to re-taking the lead, McTominay forcing a diving save from Aaron Ramsdale.
Arteta was booked by referee Anthony Taylor just after the half-hour mark as emotions got the better of him but the first half ended all square after few clear-cut chances.
Arsenal were again first to threaten after the break, pouring forward in search of another goal and they took the lead in the 53rd minute.
Christian Eriksen stood off England's Saka, who shifted the ball onto his left foot and fired unerringly past David de Gea in the United net from outside the box.
But a pulsating game took another twist when United drew level just six minutes later.
Ramsdale spilled the ball from a United corner and Lisandro Martinez threw himself at it, looping a header into the net.
Arsenal regrouped and Saka hit the post in a near repeat of his goal as De Gea watched nervously.
De Gea made a fine save when Nketiah blasted at him from close range as the clock ticked down, with United unable to control the ball for sustained spells.
United were close to holding out for the draw but Arsenal took all three points when Nketiah scored his second of the afternoon as a lengthy VAR check ruled him onside.