Arsenal manager Arsene Wenger told the club website that defender Per Mertesacker has yet to return to training ahead of the weekend match with Chelsea after sustaining an ankle injury: "Last week against Reading, Per Mertesacker got injured and he has not been out [training] since. He’s still in the treatment room and I don’t know if he will be available or not. [He is] 50/50 [to start against Chelsea] at the moment."