Arsenal manager Arsene Wenger was left counting the cost of qualification for the Champions League knockout stages as Kieran Gibbs suffered a fractured metatarsal and William Gallas was left facing a race to be fit for Sunday's clash with Chelsea.
The Gunners recorded a comfortable 2-0 victory over Standard Liege which secured safe passage into the last 16 at the top of Group H after first-half goals from Samir Nasri and Denilson - but that progress was overshadowed by the latest injury to Gibbs, who hobbled off in the final minutes following a hefty challenge from Eliaquim Mangala.
Looking forward, Wenger said: "We have normally the advantage to play the second leg at home, so let's get our injured players back and get in a strong position in the Premier League, that is important as well for the confidence of the team."
England Under-21 full-back Gibbs had only just returned to fitness from an injury to his right foot suffered while away on international duty, and Arsenal confirmed he had now suffered a fracture to the first metatarsal on his left foot.
The defender will have surgery on Wednesday, which is set to rule him out for at least two months.
As Gibbs had been filling in for French international Gael Clichy, sidelined by a back problem, Arsenal must now head into the clash against Barclays Premier League leaders Chelsea without an experienced left-back.
Armand Traore or more likely veteran Mikael Silvestre will deputise, although the versatile Emmanuel Eboue could also drop into defence.
Gallas, meanwhile, went off at the break with a combination of an ankle problem and a lump above his eye following a clash of heads with Andrey Arshavin, which also left the Russian needing staples to close a bloody gash.
Wenger hopes Gallas will be fit to face his former club on Sunday, and at least the Arsenal manager can now give some fringe players the chance to impress with the pressure off in Olympiacos next month.
"There are two competitions in the Champions League - one is the championship and one is a cup," the Gunners boss said. "We move now from the championship to the cup competition and that means it is different psychologically and we go now into a period when every minute is important. We want of course to adapt to that."
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