Title favourites Arsenal came from behind to go seven points clear at the top of the Premiership table.
Eidur Gudjohnsen gave Chelsea the lead after 27 seconds, controlling Geremi's cross before firing past Jens Lehmann.
Dennis Bergkamp's exquisite pass gave Patrick Vieira the chance to level.
Arsenal were gifted the winner when Neil Sullivan's error allowed Edu to fire home and Chelsea's misery was complete when Gudjohnsen was sent off.
With Chelsea coach Claudio Ranieri identifying the game as one his side had to win, he could not have asked for a better start with their opening goal.
It stemmed from Patrick Vieira losing control in midfield and Geremi made him pay a heavy price as he made ground to play in a cross from the left which was touched on by Adrian Mutu for Gudjohnsen to bring down and smash past Lehmann.
27 secs: Gudjohnsen gives Chelsea the lead
15 mins: Vieira levels for Arsenal
20 mins: Edu cashes in on Sullivan error to put Arsenal ahead
60 mins: Gudjohnsen sent off
Chelsea's voracious work-rate would not allow Arsenal to settle on the ball early on but on 15 minutes the Gunners produced some sparkling football to equalise.
Robert Pires' run created space down the middle and Dennis Bergkamp's sumptuous pass with the outside of his right foot found Vieira exploiting the yawning gap to atone for his earlier error by slotting the ball past Sullivan for his first goal of the season.
Arsenal turned the game round on 20 minutes when Sullivan competely misjudged Gilberto's inswinging corner and the ball fell perfectly for Edu to hammer his second Premiership goal of the season from four yards out.
Chelsea probed for an opening, with Wayne Bridge teasing in a cross from the left which was touched by Kolo Toure and shovelled round for a corner by Lehmann.
John Terry then sprung the offside trap but after chesting down Claude Makelele's cute chip, his shot lacked power to test Lehmann from ten yards.
Mutu burst into the Arsenal box at the start of the second half, only to lose his footing as he tried to check inside Toure.
Gudjohnsen got Chelsea off to a flying start
Chelsea were asking questions of the Arsenal defence but with Sol Campbell restored after missing England's midweek friendly, they presented a formidable barrier.
The Blues had a sight of goal on 58 minutes when Makelele speared in a wicked free-kick which both Mario Melchiot and William Gallas failed to make contact with in front of goal.
Chelsea's hopes of getting back suffered a body blow on the hour when Gudjohnsen's first half booking for an obvious dive caught up with him. The Icelander clipped Gilberto's heels and was shown a second yellow by referee Mike Riley.
As Chelsea laboured to find a route back in Gilberto was twice denied by Sullivan in the closing stages.
Chelsea: Sullivan, Melchiot, Terry, Gallas, Bridge,
Geremi (Cole 73), Parker (Gronkjaer 62), Lampard, Makelele,
Mutu (Hasselbaink 73), Gudjohnsen.
Subs Not Used: Ambrosio, Desailly.
Sent Off: Gudjohnsen (60).
Booked: Gudjohnsen, Mutu, Terry, Lampard.
Arsenal: Lehmann, Lauren, Campbell, Toure, Clichy, Edu, Silva,
Pires, Vieira, Bergkamp (Ljungberg 78), Henry.
Subs Not Used: Stack, Reyes, Cygan, Kanu.
Booked: Lauren, Henry.
Referee: M Riley (W Yorkshire)