Mikel Arteta suffered his first defeat in charge of Arsenal after late goals from Jorginho and Tammy Abraham earned Chelsea a dramatic 2-1 victory at Emirates Stadium.
Pierre-Emerick Aubameyang's second goal in as many games put the Gunners ahead and it looked as though Arteta's arrival had rejuvenated the Arsenal midfield as they dominated large spells of Sunday's game.
But a mistake by Bernd Leno allowed Jorginho – arguably fortunate not to have been sent off – to equalise with seven minutes of normal time left on the clock and Frank Lampard's eventful first season in charge of the Blues took another twist when Abraham scored a breakaway winner four minutes later.
The victory is only Chelsea's third in their past eight Premier League matches but relieves the pressure on Lampard, while Arteta has taken just one point from his first two games as Arsenal boss.
David Luiz fired wide for Arsenal with an overhead kick after five minutes, but it was his former club who controlled the early tempo and Mason Mount tested Leno with a rising shot from 10 yards.
Chelsea's solid start crumbled after 13 minutes when Calum Chambers flicked Mesut Ozil's corner to Aubameyang, who was allowed to fire a header past Kepa Arrizabalaga from inside the six-yard box unchallenged by his marker, Emerson Palmieri.
Chambers left the field 10 minutes later with an apparent knee injury while Frank Lampard sent on Jorginho for Emerson, and those changes gave the visitors some momentum even though they trailed at the interval.
Chelsea continued to improve in the second half and Abraham might have equalised from 12 yards had David Luiz not made a timely block to divert his low drive.
Abraham then sent a free header tamely into Leno's hands, but the Gunners goalkeeper made a howler moments later, punching thin air as Mount's cross drifted to the far post where Jorginho bundled it into the net.
Arsenal went in search of a winner but were caught out when Willian launched Abraham into a counter-attack, the Blues striker exchanging passes with his Brazil international team-mate before sliding the ball through Leno's legs and into the net from six yards out to clinch a much-needed win for his side and condemn Arteta to defeat in his first home match in charge.
Late winner lets Lampard breathe again
Six defeats in eight games would have left Lampard's position under quite strong scrutiny going into the new year, but the spirit his side showed in turning around a tough London derby will have reassured owner Roman Abramovich that his former midfielder can motivate this squad.
