Arsenal's Shkodran Mustafi "could be out for a while" after suffering a suspected torn ligament during Germany's final World Cup Qualifier against Azerbaijan.
The 25-year-old centre-back, who has started six of the Gunners' matches so far this season, was withdrawn in the first half of the 5-1 win in Kaiserslautern clutching his right groin and thigh area.
Mustafi pulled up and went to ground in the build-up to Azerbaijan's equalising goal, and he needed treatment before leaving the field in the 36th minute. He was replaced by Mattias Ginter.
Arsenal's next match is against Watford on Saturday October 14 and, with Laurent Koscielny and Calum Chambers both nursing knocks, Mustafi also appears to be a doubt for the evening kick-off at the Emirates.
Germany boss Joachim Loew said: "It doesn't look good, it looks like he had torn a ligament. We're waiting for a full diagnosis, but it looks like he will be out for a while."
Mustafi was rested as Germany beat Northern Ireland last week to assure top spot in their group and a place in next year's World Cup finals in Russia, but was he brought into the side for Mats Hummels as Low switched to a back-three.