Joachim Low said he thinks the Arsenal defender suffered muscle tear in a 5-1 victory over Azerbaijan.
Arsenal could be set to be without the most expensive defensive signing in the club's history for an extended period, after Germany manager Joachim Low confirmed that Shkodran Mustafi picked up a 'more serious' injury playing for Germany against Azerbaijan on Sunday.
The defender limped off late in the first half with what appeared to be a hamstring injury, as Die Mannschaft coasted to a 5-1 victory to finish top of their World Cup qualifying group with a 100% record - with an astonishing goal difference of +39 from their ten games.
Quoted by ESPN FC after speaking to reporters at the end of the game, Germany coach Low admitted: "I think Mustafi has a muscle tear. It looks a bit more serious. This will probably force him to have an extended layoff."
The news will come as a major blow for Arsene Wenger, whose side have only just started to get their defence into shape after a dreadful start to the season which saw them concede eight goals in their first three games.
The Gunners have since gone five games without conceding in domestic competition, although only Chelsea provided a true challenge to their back line in a run of fixtures which also saw Wenger's side host Doncaster, West Brom, Brighton and Bournemouth - with the latter three combining for just 15 goals in their 21 games this season.
The next handful of league fixtures see the north London side face the relatively unthreatening trio of Watford, Everton and Swansea, while facing Norwich and FK Crvena Zvezda (twice) in the Europa League - but Bonfire Night ushers in a much trickier run, with back-to-back games against Manchester City and Tottenham.