Manchester United survived the second-half dismissal of Paul Pogba to end Arsenal's 12-game winning run at home in the Premier League with a 3-1 victory at Emirates Stadium - but only thanks to the brilliance of David de Gea.
The Premier League heavyweights took part in a slugfest in the English capital, with Jose Mourinho's side somehow surviving some seriously heavy punishment to run out victors and close the gap on leaders Manchester City to five points.
United capitalised on some poor defending to race out to a 2-0 lead, Antonio Valencia and Jesse Lingard punishing early Arsenal mistakes, before Alexandre Lacazette - a surprise selection after Arsene Wenger had said he would be sidelined for the fixture - halved the deficit early in the second half.
However, Arsenal's bid for a third straight home win over their rivals ran aground against the rock-like De Gea, who produced a string of outstanding saves either side of the break to keep his team in front.
Lingard's second of the game in the 63rd minute restored a two-goal cushion and, while Pogba saw red for a stamp on Hector Bellerin that will rule him out of next weekend's Manchester derby, United held firm to triumph on their travels.
Arsenal will wonder quite how they ended up with nothing from a pulsating encounter, albeit their problems were all of their own making when a side who had previously only conceded four league goals at home in the season gifted their opponents a 2-0 lead inside 11 minutes.
Laurent Koscielny's careless cross-field pass inadvertently set up Valencia's opener before Shkodran Mustafi's carelessness in possession led to Lingard scoring, the England international not even having to break stride to convert Anthony Martial's exquisite reverse pass in behind.
Yet despite the disastrous start, plus the loss of the injured Mustafi that forced a change in formation and a switch to a flat-back four, the hosts peppered United's goal for the remainder of the half.
Lacazette was twice denied by De Gea, who relied on his reactions to keep out a close-range toe poke before needing assistance from the crossbar to keep out another on-target attempt from the Frenchman.
The visiting goalkeeper was so good he even denied Romelu Lukaku from scoring for the first time in open play at the Emirates, diving to his left to make sure his team-mate's inadvertent touch on a dangerous free-kick did not nestle in his own net.
While Lacazette did finally beat De Gea when Aaron Ramsey's poor touch from Alexis Sanchez's cross dropped perfectly into his path, the Spaniard continued to defy a home team smelling blood.
United's last line of defence not only kept out Lacazette's low drive at his near post but also prevented Sanchez from tapping home the rebound, stretching out his right leg to make a crucial block.
The double save proved a turning point as United landed the sucker punch on the break, Lingard, who had already hit the post after the break, tapping home from close range.
After providing the assist, Pogba left his side to finish the game a man light when he lunged in and caught Bellerin. The red card did not prove costly in terms of the outcome, but the Frenchman will now miss his team's next three domestic games, including next weekend's huge derby against City.
