Jack Butland's return from injury has been put on hold, with the Stoke City goalkeeper set to undergo an MRI scan after pulling out of his planned comeback appearance.
The 23-year-old has not featured in a competitive game for Stoke since fracturing his ankle while on international duty with England in March.
He had been due to start for the club's Under-23 side against Reading on Friday night, but was forced to pull out of the game after feeling some discomfort during the warm-up.
City assistant boss Mark Bowen, however, remains hopeful that the setback may only be a minor one.
"All I'll say is, without wanting to panic anyone, he went down to Reading and felt something in the warm up," Bowen told BBC Radio Stoke.
"We won't know the extent until he has an MRI scan, but he was intelligent enough to calm his enthusiasm.
"He's played on the safe side. We won't know the damage until he has the scan.
"We're not sure. Maybe it will be another injection, but we need the experts to look at the scan."