The midfielder is returning from a serious ankle injury.
Wenger said: "We have to be cautious because he has been out for a long time and it takes a while to get back to match fitness.
"I have never had any doubts, but when you are so young, and to be out for that length of time, is a good test of mental strength. 'I didn't doubt he would be back, but you would have to ask him if it crossed his mind - I would say yes.
"I am certain he will be a better player. If you have this type of injury after the age of 25 it is different. 'After three months competition I am sure he will be back to his best. It takes time to find that little burst again."