Birmingham are sweating over the fitness of on-loan Barcelona midfielder Alexander Hleb ahead of Sunday's derby match at Aston Villa.
The former Arsenal player suffered a twisted knee during the second half of Saturday's 2-0 home success over Blackpool.
Blues boss Alex McLeish said: "At half-time I said to Alex 'give me 15 minutes of magic and we will get you off'. It went a bit longer than that and all of a sudden he had a little twist in his knee which we are concerned about.
"We have to wait to see how it is but he is a brave guy. I just hope there is no serious damage."
He added "He took a pain-killing injection on Saturday morning in his ankle so we will be looking for him to be a quick healer.
"I was going to take him off maybe five or six minutes earlier. I wish I had now."
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