Birmingham's key defender Scott Dann is facing a spell out of action after manager Alex McLeish confirmed he has torn a hamstring.
Dann needed a fitness test before playing in last night's Carling Cup semi-final clash at West Ham.
But the former Coventry player had to be substituted at half-time of Birmingham's 2-1 first leg setback.
Now he looks certain to miss at least Sunday's derby with Aston Villa at St Andrew's and McLeish said: "We hope Scott isn't too bad but he has definitely torn a hamstring. He passed a fitness test on the morning of the cup game. Sometimes players want to play through even a wee niggle.
"Sometimes they get away with it but sometimes they can end up with a bad injury."