Arsene Wenger: A fact is a fact, Diego Costa got Mertesacker sent off

Arsene Wenger was left to rue the impact of Diego Costa as 10-man Arsenal were undone by Chelsea yet again.

Costa in September tussled with Laurent Koscielny and Gabriel, who was sent off, and drew a foul from Per Mertesacker which saw the German dismissed at the Emirates Stadium in Chelsea’s 1-0 win.