Jack Wilshere's latest return from injury has been delayed on medical advice, with Arsenal boss Arsene Wenger saying it was "very difficult" to know for sure when the midfielder was likely to be back.
Wenger had been confident that the England international would be fit to play in Saturday's Premier League game against Reading at the Emirates.
The player had been ordered to rest by medical staff after inflammation of his ankle was diagnosed in a routine scan.
Wenger said he hoped Wilshere, 21, would return in mid-April, but was cautious about rushing him back because of his injury record.
"Honestly, is very difficult to say [when he will be back] - maybe in two weeks," he said. "It is an inflammation of his bone, and we have such history with him so we are a bit more cautious.
"We have deferred his rehab by one week. We gave him one more week rest because it was wise medically to do it.
"We will rest him when it is needed. He knows he has to take care of his future. He is a very young player, he accepts it."
The earlier ankle problem that kept Wilshere out of action for 17 months saw Wenger talk of several possible return dates before he finally made a comeback.
However, there are no suggestions that surgery will be required on the latest injury, and the manager said he would have no problem with Wilshere being called up to play for England in friendlies this summer if he regained full fitness.
"He doesn't need any special treatment," he said. "You just have to be cautious with the inflammations of his ankle at times. He has been out for 17 months, so he wants to play. I understand that.
"If he is selected [to play for England this summer], he will go. It depends what kind of shape he will be in. If he has no problems, why not?"
Wenger went on to suggest that the pressure on Wilshere to boost the England team was unreasonable, saying: "A country doesn't depend on one player, no matter how good he is.
"Jack is a fantastic player, but it would be too much pressure on him to say England's future depends on him."
Wenger confirmed that Lukas Podolski and Bacary Sagna are fit to return against Reading, but Theo Walcott is injured and Kieran Gibbs is struggling to shake off flu.
He said he had made a decision on who would start in goal, but would not reveal whether Lukasz Fabianski would retain his place ahead of Wojciech Szczesny.