Arsenal boss Arsene Wenger says midfielder Jack Wilshere may not be fit for the start of the 2012-13 season.
The 20-year-old has not played competitively for the Gunners since facing Fulham in May 2011.
Wilshere has already been ruled out of Euro 2012, but Stuart Pearce is keen to include him in Team GB's Olympics team.
However, Wenger said: "I do not want to set the Olympics as a target because I do not know whether Jack will be fit to start at the beginning of the season."
Wilshere injured his right ankle last summer and underwent successful surgery, only to suffer a stress fracture during his rehabilitation in January.
The midfielder's hopes of playing again before the end of the season have subsequently faded, along with plans to be involved with England in Poland and Ukraine this summer.
Wenger is now concerned that Wilshere could miss the start of the Gunners' pre-season training.
The Frenchman added: "When we start pre-season training on 9 July, if he can join in, then we have won the battle, but that is not guaranteed.
"You get the first knock, but think: 'OK, at least I will be ready for the Euros.' Then you have to convince him: 'Look my friend, it will not work for the Euros.' You knock him down again.
"Then you set him another target - the Olympics. But if he doesn't make it, he will lose a complete appetite for rehab because it's difficult.
"Let's take our time and not set any specific targets.
"The most important thing for him is to focus on day-to-day work and see if he can get better."
Wenger is more upbeat about the fitness of winger Theo Walcott, who limped out of last weekend's goalless draw against Chelsea with a hamstring problem.
The Gunners boss said: "It is less serious than we thought. He has a small chance to play in the last game of the season.
"For the Euros, he is definitely available."