Arsenal's defensive injury crisis has deepened after two of their full-backs succumbed to injury.

Left-back Nacho Monreal did not travel with the rest of the Arsenal squad to Germany today ahead of tomorrow's Champions League clash with Borussia Dortmund, although the club insist that the player will not be sidelined for a lengthy period.

The Gunners are already without Mathieu Debuchy after he suffered twisted ankle ligaments during Saturday's draw against Man City.

That means Calum Chambers, Per Mertesacker, Laurent Koscielny and Kieran Gibbs are the only fit defenders in the squad, although midfidelder Mathieu Flamini can also fill in at full-back in an emergency.

Chambers's acquisition from Southampton was the only defensive addition made by Arsenal manager Arsene Wenger during the summer transfer window.