Arsenal skipper Mikel Arteta is facing six weeks on the sidelines.
Arteta could be out for six weeks after limping off with a calf problem in Wednesday's 2-0 home win over Borussia Dortmund, while goalscorer Yaya Sanogo also suffered a hamstring injury.
They join Arsenal's growing injury list, with Jack Wilshere facing surgery and a three-month lay-off and Theo Walcott, Mathieu Debuchy, Danny Welbeck, Mesut Ozil and Wojciech Szczesny also out.
And boss Wenger said: "Mikel Arteta doesn't look good - it's a calf. I think he will be out for a while.
"The injuries are difficult to take on the chin. We go into many games and we need as many as possible available. The injury situation is a problem because we have many games and we lost two players tonight.
"Arteta again has a calf problem and that looks quite serious and we lost Sanogo as well on a hamstring problem."
