The 20-year-old midfielder has not featured at all for the Gunners this term because of an ankle injury which required surgery.
Wenger said: "We try to keep the hope alive for him without taking too many risks.
"That means we adapt day to day to manage him, to improve his physical state and get him fit as quickly as we can without taking too big a risk, which means when he has pain we stop him.
"In the next four or five weeks we will know more - and the next three weeks will be decisive.
"You would think a player who wants to play in June will have to be competitive at the end of April.
"The next three weeks will decide if he can go to the Euros."