Laurent Koscielny appeared to suffer a new injury setback after hobbling off in Arsenal Under-21's Checkatrade Trophy defeat to Portsmouth at Fratton Park.
The defender has been fighting back to fitness after rupturing his Achilles tendon against Atletico Madrid in May.
He managed 45 minutes in the side's previous Checkatrade Trophy game against Derby, but had to be removed five minutes from time against Pompey.
He seemed to pull up without contact from a player, and a physio ran on to help him limp off the pitch. The injury occured just after Portsmouth's Andre Green had struck what proved to be the winner to eliminate Arsenal Under-21s from the Checkatrade Trophy.
Brett Pitman had put the hosts ahead, only for youngster Bukayo Saka to conjure a stunning equaliser at a sparse Fratton. The Achilles injury ruled Arsenal's captain out of France's World Cup campaign in the summer, where they went on to lift the trophy.
Since joining the club from French side Lorient in 2010, Koscielny has gone on to make 324 appearances for the Londoners, scoring 24 goals.
He was also a key part of the side that won back-to-back FA Cups in 2014 and 2015.