The trio reported back from international duty with injuries. Gallas is struggling with an hamstring injury, Sagna have a knee problem and Bendtner is struggling with a ankle problem.
Wenger said: “Unfortunately we have lost some players over the 10 days — William Gallas, Bacary Sagna and Nicklas Bendtner.
“These are heavy losses and we have to compensate them.
“Fortunately the three of them don’t look to be out for a long, long time but they will be out for the weekend game and I think the game on Tuesday.
“As well as them, Johan Djourou got concussion during his game with Switzerland and will be assessed tomorrow to see if he is available.
“He does not look too bad and he could have a good chance to play.
“I am still waiting for Robin van Persie to come back so I don’t know about him. However, he should be okay.
“He went with a muscle problem but he came on after 56 minutes last night and, from the reports I got, he should be all right. Both of them will be assessed.
“Also I am told Cesc Fabregas has a broken nose. It should not stop him playing. He is here now and is being assessed.”