Costa’s goal gives Blues derby victory over 10-man Arsenal

Arsenal 0 Chelsea 1

Diego Costa’s goal gave Chelsea victory over 10-man Arsenal at the Emirates Stadium.

Costa struck on 22 minutes – shortly after Per Mertesacker was sent off for a foul on the striker.

Willian led a counter-attack and cleverly aimed a pass in behind Mertesacker for Costa, who would have been through on goal had the Gunners captain not brought him down.

Mertesacker was duly shown the red card by referee Mark Clattenburg, and the home fans reacted angrily to Arsenal boss Arsene Wenger’s response to the dismissal, 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.

Chelsea are now unbeaten in nine Premier League matches against Wenger’s side, who would have returned to the top of the table had they won.

The visitors’ win lifted them up to 13th and continued their improvement since Guus Hiddink took charge.

Having found themselves a goal and a man down, Arsenal struggled to create chances – although Mathieu Flamini missed one seconds before half-time when he hurriedly hooked the ball over after being found unmarked inside the box by Aaron Ramsey.

Petr Cech, playing against his former club, was the busier keeper – and showed he remains a world-class operator.

Cech produced fine saves to deny Willian and Costa, Ivanovic had a header cleared off the line, and Chelsea should arguably have been awarded a second-half penalty when ex-Arsenal man Cesc Fabregas was barged over by Laurent Koscielny.