Birmingham have recalled goalkeeper Colin Doyle from his loan spell at Coventry following the back injury suffered by Ben Foster on international duty.
Foster left the England squad on Tuesday after sustaining the problem ahead of Wednesday night's friendly with Hungary at Wembley.
Birmingham have not yet ruled Foster out of the Barclays Premier League opener against Sunderland at the Stadium of Light on Saturday and expect to know the extent of the injury within the next 24 hours.
But manager Alex McLeish is short of cover, with Northern Ireland veteran Maik Taylor the only other senior goalkeeper in the squad.
Doyle only joined Coventry on Tuesday on a one-month deal, making his debut in their Carling Cup defeat against Morecambe.