Alexandre Lacazette crafted a wonderful 14th-minute opener as Maurizio Sarri's side, not for the first time this season, wilted under the pressure of a London derby.

Club captain Laurent Koscielny's attempt to head Sokratis Papastathopoulos's volleyed pass six minutes before half-time spun off his shoulder and beat Chelsea goalkeeper Kepa Arrizabalaga.

It was the former France defender's first goal since rupturing an Achilles tendon last season and Chelsea was unable to respond.

Sokratis powered wide unmarked from an eighth-minute corner before centre-back partner Koscielny forced a point-blank save from Kepa, who was grasping at air when Lacazette turned sharply and clipped past him at his near post.

Sead Kolasinac played Pedro haphazardly onside to almost loft an 18th-minute equaliser for Chelsea, although the left-back made himself more useful in attack with a delicate cross that Pierre-Emerick Aubameyang nearly converted with a wonderful overhead kick.

Koscielny's fortuitous conversion off his shoulder was not so picturesque but it was nevertheless rapturously received at Emirates Stadium.

Slack set-piece marking at the other end saw Marcos Alonso head against the post, pursuing a lifeline Chelsea scarcely deserved.

Chelsea enjoyed sustained possession in the Arsenal half early in the second period but created little, with Koscielny in particular defending impeccably.

Aaron Ramsey tried to prod the goal his endeavours deserved in the 64th minute after Kolasinac raided into the Chelsea box.

Blues substitute Ross Barkley had a rasping strike blocked before Arsenal made an enforced change due to Hector Bellerin collapsing with a seemingly serious knee injury - a rare blot on an outing far removed from last weekend's loss at West Ham.