Manchester United ruthlessly punished defensive errors to become the first side to win a league game at Arsenal since January in one of the matches of the season so far.
Jose Mourinho's side were reduced to 10 men late on when Paul Pogba was sent off for a dangerous tackle and they were aided by a stunning goalkeeping display by David de Gea throughout.
But they did telling damage early on when Antonio Valencia pounced on a loose Laurent Koscielny pass to drill the opener, before Jesse Lingard side-footed a second after robbing Shkodran Mustafi to link smartly with Romelu Lukaku and Anthony Martial.
The strikes meant United had scored as many goals in 11 minutes as they had in eight away fixtures against the Premier League's so-called 'big six' clubs.
An end-to-end first-half, which delivered 20 shots on goal, saw Arsenal hit the woodwork through Alexandre Lacazette and Granit Xhaka during a frenetic goalmouth scramble, before De Gea denied Hector Bellerin, Sead Kolasinac, and spectacularly prevented a Lukaku own goal.
The Spaniard could do nothing about Lacazette's simple finish on 48 minutes but after Lingard had hit the post in a breathless start to the second half, De Gea produced an unbelievable double save from Lacazette and Alexis Sanchez.
His heroics maintained the advantage during an opening 15 minutes to the second half which saw United have just 26% of possession, but Lingard was on hand to tap in a third on 63 minutes after good work by Pogba.
Pogba was dismissed when he mistimed a tackle to effectively stamp on the back of Bellerin's leg, and the Frenchman will now miss the Manchester derby next Sunday.
But his moment of woe felt merely a footnote in a riveting encounter which moved second-placed United to within five points of their city rivals.
Mourinho has garnered a reputation for defensive set-ups on trips to the league's traditional big clubs but his side went after their hosts early on, hounding possession high up the pitch to great effect.
Their opening two goals owed much to slack use of possession by the home side but needed clinical finishes, notably when Martial cleverly flicked into the path of Lingard for the second.
The reward for their adventure secured a first win for Mourinho in his past 12 away fixtures against the 'big six'.
He could be forgiven for not enjoying seeing Arsenal fire 33 shots at goal and said he later told De Gea - who equalled the league record for saves in a match - he had witnessed the "best from a goalkeeper in the world".
Arsene Wenger also labelled De Gea "absolutely outstanding" but while his brilliance points to United riding their luck at times, they were impressive in offering a balance between defence and attack.
Nemanja Matic was consistently well placed, never more so than when blocking a goal-bound Aaron Ramsey shot with the score at 2-0.
And the presence of the defensive midfielder once again freed Pogba, who in bursting into the box to lay on Lingard's second now has five assists this season, surpassing his four in the previous campaign.
Whether Mourinho will choose to live so dangerously against Manchester City next week remains to be seen, but those watching from a neutral stance would be fortunate to see a game as good as this one again.
Wenger spoke of a "good performance" and "impeccable attitude" from his players but he will be familiar with this feeling.
Only twice in 18 meetings with Mourinho has he got the upper hand and the charitable way in which his side gave away goals will not sit well.
Koscielny's cross-field pass and Mustafi's indecision ultimately left a mountain to climb if Arsenal were to record a 12th straight home win in the league.
The ease with which Pogba sauntered into the area to create a third just as Arsenal were seeking to build on Lacazette's goal also smacked of weakness.
Arsenal can justifiably feel aggrieved by a penalty shout that was turned down late on when Danny Welbeck was caught by Matteo Darmian but by that point, the 10 men of United had finally managed to calm a frantic affair.
Wenger's side drop out of the Champions League qualification places into fifth. They were superb going forward at times and will scratch their heads as to how they only found the net once but, not for the first time, it was at the other end where their shortcomings showed up.