Arsenal will be without Theo Walcott, Gervinho and Laurent Koscielny for Wednesday's Champions League encounter against Olympiakos.

The England winger Walcott picked up a knee injury late on during Arsenal's 3-0 win over Bolton on Saturday and he missed training on Tuesday. Gervinho has a hamstring starin and Koscielny an ankle problem.

However, Arsène Wenger is hopeful all three will recover in time to be fit for this weekend's north London derby with Tottenham Hotspur at White Hart Lane.

It means Arsenal go into their tie with nine players missing through injury. Besides the three already mentioned, Sébastien Squillaci has a knee problem, Jack Wilshere a long-term ankle injury, Abou Diaby an ankle problem, Yossi Benayoun a groin strain, Thomas Vermaelen an ankle injury and Johan Djourou a hamstring problem.

With four of their five central defenders absent, Wenger is set to play Alex Song at centre-half alongside Per Mertesacker.

Arsenal are looking to follow up a 1-1 draw away to Borussia Dortmund with their first win of this season's group stages of the Champions League.