Arsenal could be missing defender Shkodran Mustafi for an extended period of time after he suffered an injury while on duty with Germany.
The centre-back was taken off in the first half of Germany's 5-1 win over Azerbaijan in a World Cup qualifier played in Kaiserslautern on Sunday.
The 25-year-old pulled up clutching at his right thigh in the 36th minute of the encounter. He was replaced by Mattias Ginter and is suspected to have torn a ligament.
"It doesn't look good, it looks like he had torn a ligament," Germany manager Joachim Loew said, as quoted by Sky Sports. "We're waiting for a full diagnosis, but it looks like he will be out for a while."
Mustafi has played five of Arsenal's seven Premier League games this season and has helped them keep four consecutive clean sheets.