The Spaniard damaged knee ligaments during the draw at Norwich.
Wenger says Rennes' refusal to sell saw the Gunner miss out on the France international.
Mesut Ozil has been Europe's most creative midfielder so far.
Aaron Ramsey made a much anticipated return through the centre of midfield.
PSG striker Edinson Cavani has scored nine goals in 15 league appearances.
Christian Eriksen has revealed that he was a huge fan of Mesut Ozil since his time at Real Madrid.
The Gunners secured a nervy victory over Sunderland before their crucial trip to Olympiakos.
Arsene Wenger says pitches and training alone not responsible for injuries
Carvalho suffered a stress fracture in his tibia in July and returned to action earlier this season.
Arsenal look to get back to winning ways as they host Sunderland in the PL on Saturday.
Sanchez is a doubt for upcoming games against Sunderland and Olympiacos.
Laurent Koscielny and Theo Walcott may be available to make the squad.
Arsenal are currently without five first-team midfielders due to injury.
Arsenal are hoping to have Alexis Sanchez back ahead of their clash against Manchester City on 21 December.
Nacho Monreal is the only Arsenal player to play every minute of Premier League football this season.
North London rivals both sent scouts to watch the winger in the Europa League match against Liverpool.
Arsenal could be without a number of first-team players for their clash against Sunderland on Saturday.
Santi Cazorla is likely to miss more than the Olympiacos game for which he was initially assessed.
Martin Keown had back problems after training during his time at Arsenal
Cazorla will undergo a scan to alleviate concerns over potential ligament damage to his knees.
Defoe picked up a hamstring injury while Larsson has a problem with his medial ligaments.
Gunners boss has reacted angrily to claims that injured Chilean star should have been rested.