An embarrassing first-half collapse saw Chelsea beaten at the Emirates for the first time in almost six years.
Two goals in three minutes early on set the tone as a Gary Cahill error allowed Alexis Sanchez the opener, and Theo Walcott then converted Hector Bellerin’s cross after the Blues defence was cut open.
Mesut Ozil made it 3-0 just before the break when he started and finished a counter-attack which left Chelsea’s two-man rearguard exposed.
Substitute Michy Batshuayi had the best chance to pull one back when he was sent clear but ex-Blues keeper Petr Cech came out quickly to block.
Arsenal had not scored against Chelsea, let alone beaten them, in the last seven league meetings between the sides, but Arsene Wenger’s side set about changing that pretty quickly.
After Santi Cazorla’s early sighter, beaten away by Thibaut Courtois, the Gunners struck in the 11th and 14th minutes.
First, Cahill presented Sanchez with a clear run on goal, and the Chilean striker duly beat Courtois, and then the Blues defence – looking rudderless without injured skipper John Terry – crumbled in the face of crisp passing, Bellerin crossing for Walcott to tap home.
Willian drilled a shot narrowly wide but Arsenal added a third as Ozil spun away in midfield to start a swift two-on-two break.
He slipped in Sanchez who returned the pass and the German hit a shot into the ground and beyond Courtois.
Blues boss Antoni Conte responded 10 minutes into the second half by withdrawing ex-Arsenal man Cesc Fabregas – much to the home fans’ delight – and switching to a 3-4-3.
But that changed little, although Pedro was denied by a terrific Bellerin challenge and Cech did well to block from Batshuayi.
Arsenal slowed their tempo down as the match wore on, their only real opportunity coming when Courtois saved from Walcott, as they earned their biggest win over the Blues since April 1997.
This post was last modified on 27/09/2016