Nacho Monreal has not travelled with Arsenal ahead of their Champions League match against Borussia Dortmund this week because of a back injury.
The defender will miss tomorrow's tie in Germany, but Goal.com reports that he is expected to recover from the problem in time for Saturday's match against Aston Villa in the Premier League.
Meanwhile, Calum Chambers is also a doubt for the opening group game after contracting a bout of tonsilitis, while Mathieu Debuchy had already been ruled out with the ankle injury that he suffered during Saturday's 2-2 draw with Manchester City.
Manager Arsene Wenger has rated the England international's chances of featuring as "50-50", with teenager Hector Bellerin on standby to start if Chambers does not recover in time.
