Arsenal manager Arsene Wenger said that Lukas Podolski would be out for around three weeks after the German forward injured his hamstring against Fenerbahce in the Champions League on Tuesday.
The Germany forward had to be stretchered off early in the second half of Arsenal's 2-0 win at the Emirates Stadium, which completed a 5-0 aggregate win in the play-off round tie.
Wenger also saw Aaron Ramsey, scorer of both Arsenal's goals, go off with a groin complaint, while Jack Wilshere took some heavy blows to his troublesome ankle late in the game.
"That's the negative of tonight. We played a heavy price on the injury front because we lost Podolski," Wenger said.
"I don't know how bad Ramsey is. I don't know how Wilshere responds to an ankle problem. We have to check that tomorrow (Wednesday) morning.
"He (Wilshere) looks all right. But Podolski is definitely out for 21 days and Ramsey, we have to check how severe his groin problem is tomorrow."
Podolski will definitely miss Sunday's north London derby against Tottenham Hotspur and faces a race to get fit in time for Arsenal's opening Champions League group-phase game on September 17 or 18.