By Chris Harris
The Spanish goalkeeper is suffering from a chest infection and has not travelled to Belgium. Neither have Robin van Persie and Denilson, both of whom sustained injuries during Saturday's 4-2 defeat at Manchester City. However they have a chance of returning for this weekend's Premier League clash with Wigan.
"Manuel Almunia is sick so he will not be with us," revealed Wenger before flying out with his 18-man squad.
"From Saturday we lost Robin van Persie with a knee problem but it is a question of days for him [until he is fit]. As for Denilson, I took him off on Saturday for a back problem. It is a question of days again for him."
Theo Walcott will not return for the group stage opener but Sanchez Watt has been named in the squad. The 18-year-old forward impressed at the Emirates Cup in August and could make his competitive debut on Wednesday.