Alexandre Lacazette's second-half penalty proved decisive as Arsenal beat Tottenham 2-1 to dent the top-four hopes of Spurs, who saw goalscorer Erik Lamela sent off.
Arsenal's preparations for the game were by no means ideal as Mikel Arteta revealed pre-match that captain Pierre-Emerick Aubameyang had been dropped for disciplinary reasons, reportedly relating to tardiness, but the Gunners were the better side from start to finish and deserved the points.
It looked like being a grating day for them after seeing Emile Smith Rowe and Cedric Soares denied by the woodwork either side of Lamela's quite remarkable breakthrough goal.
Martin Odegaard restored parity on the stroke of half-time and Lacazette completed the turnaround from the spot in the second period to move Arsenal back to within four points of its seventh-placed rival, with Lamela's dismissal 14 minutes from time hampering Tottenham in its late rally.
Spurs struggled to get out of their own half during the early exchanges and were fortunate to remain on level terms when Smith Rowe's dipping 25-yard strike hit the crossbar, while they lost Son Heung-min to injury soon after.
But Tottenham finally showed some attacking intent just past the half-hour mark and it led to their remarkable opener, Lucas Moura teeing up Lamela – Son's replacement – to produce a 'rabona' finish that went through Thomas Partey's legs and found the bottom-right corner.
Arsenal's frustration amped up as Cedric was the next Gunner to be denied by the frame of the goal, but a deserved equaliser did arrive just before the break when Odegaard turned in Kieran Tierney's cross with the aid of a deflection.
The hosts continued to control proceedings but had been struggling to break Spurs down before winning their penalty just after the hour – Davinson Sanchez clumsily fouling Lacazette after the Frenchman had unsuccessfully swiped at the bouncing ball.
Lacazette coolly converted the resulting spot-kick and Spurs' hopes suffered a major blow when Lamela caught Tierney in the face with a stray arm to earn him a second yellow card.
Late scares saw a Harry Kane header ruled out for offside and the same man hit the base of the post from a free-kick, but Arsenal held on to end their five-match winless run in the derby.