Arsenal midfielder Jack Wilshere has suffered a setback in his return from an ankle injury, according to Gunners manager Arsene Wenger.
The England international sustained the injury during Arsenal's friendly encounter with the New York Red Bulls towards the end of last month.
Initial reports had suggested that the 19-year-old would be fit for the start of the new season, but he failed to make Arsenal's 0-0 draw with Newcastle United.
It now appears that Wilshere will miss his side's trip to Old Trafford this Sunday and could be absent from England's Euro 2012 qualifiers against Bulgaria and Wales in September.
"I don't know if we are back to square one or for how long he will be out," said Wenger.
"He's in a boot again, so that means he will at least be out for two or three weeks."
Wilshere made his England debut in 2010 against Hungary and has gone on to gain five caps.