Arsenal still seeking a way to beat Blues

Arsenal manager Arsene Wenger dismissed suggestions his side has a mental block regarding London rival Chelsea following Sunday's 1-0 home loss that carried an air of deja vu.

Arsenal was bidding to return to the top of the Premier League standing, but was left in third place after Per Mertesacker was sent off and Diego Costa scored to lift the visiting side to victory.

Arsenal has not beaten Chelsea in nine league games and has not scored against it in the league in nine hours and 32 minutes of play, but Wenger said Mertesacker's 18th-minute dismissal, for a last-man foul on Costa, made it impossible to compare the game with previous fixtures.