Latest: Arsenal 0 Chelsea 1 – Costa strikes again as Blues lead against 10-man Gunners

Diego Costa’s 22nd-minute goal put Chelsea ahead in the derby at the Emirates Stadium shortly after Arsenal captain Per Mertesacker was sent off for a foul on the Blues striker.

The Gunners were reduced to 10 men following a Chelsea counter-attack led by Willian, who cleverly aimed a pass in behind Mertesacker for Costa, who would have been through on goal had the defender not brought him down.[phone][/phone]

Mertesacker was duly shown the red card by referee Mark Clattenburg, and the home fans reacted angrily to Arsenal boss Arsene Wenger’s reaction to the sending-off, which was to send defender Gabriel on in place of forward Olivier Giroud.

Seconds later, Costa drifted away from Gabriel to nudge home Branislav Ivanovic’s right-wing cross – his sixth goal in as many games.

Arsenal keeper Petr Cech, playing against his former club, had earlier denied Willian at point-blank range and pushed away a shot from Oscar.

Chelsea: Courtois; Ivanovic, Zouma, Terry, Azpilicueta; Mikel, Matic; Willian, Fabregas, Oscar; Costa.
Subs: Begovic, Cahill, Baba Rahman, Loftus-Cheek, Traore, Hazard, Remy.