Arsenal forward Lukas Podolski will miss Sunday's North London derby with Tottenham after suffering a hamstring injury in the Champions League qualifying defeat of Fenerbahce.
The Germany international is expected to be out for three weeks after pulling up in the opening minute of the second half of the 2-0 second leg win over the Turkish side which completed a 5-0 aggregate triumph.
Manager Arsene Wenger said: 'We paid a heavy price on the injury front because we lost Podolski.
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Blow: Lukas Podolski added to Arsenal's injury woes as the striker was taken off on a stretcher
'Podolski's definitely out for 21 days.'
Aaron Ramsey scored both goals on the night as Arsenal completed qualification for a 16th successive season in the Champions League group stages.
But the Welshman was one of the players who felt the impact of a bruising encounter, going off before the end with a groin problem as the Gunners finished the game with 10 men.
Midfielder Jack Wilshere was also the victim of some meaty challenges, particularly from Raul Meireles and Bruno Alves, which he walked away from gingerly.
Soldiering on: Jack Wilshere clutches his ankle but he refused to come off as Arsenal beat Fenerbahce
Wenger added: 'I don't know how bad Ramsey is. I don't know how Wilshere responds. We have to check that tomorrow morning.
'The two tackles on Wilshere were disappointing, but he looks all right.
'Jack should be all right for Sunday. I'm hopeful on Aaron as well.
'I took him off with three or four minutes to go, but I don't know how bad it is. He wanted to stay on."
Wenger had wanted to take Wilshere off, due to the England midfielder's history of ankle problems, but the player was determined to play on.
'I wanted to take him off, yes,' Wenger said.
Goal hero: Aaron Ramsey appeared to leave the game before the end holding his groin
'I would've played with 10 men. We were 2-0 up, they had to score five goals in 10 minutes. Even with 10 men we could have avoided that.'
With injuries already to Mikel Arteta and Alex Oxlade-Chamberlain, further fitness concerns throw a further spotlight on Wenger in the final days of the transfer window.
There were reports Juan Mata Senior, father and agent of the Chelsea playmaker, was at the Emirates Stadium for the match.
Wanted: Arsenal boss Arsene Wenger has admitted his interest in Chelsea star Juan Mata
Following the Spain playmaker's omission from the Chelsea starting line-up at Manchester United on Monday night, rumours circulated he was available for transfer.
Chelsea boss Jose Mourinho denied those suggestions and Wenger believes it would be a long shot.
'I like him,' said Wenger, who was beaten to the former Valencia playmaker's signature by Chelsea two years' ago.
'I watched the game last night and I've heard, like you, Juan Mata could be on the market.
'There is anyway in England a reluctance to sell to each other.'