Birmingham City centre-half Gavin Gunning is set for a lengthy spell on the sidelines after suffering posterior cruciate ligament damage on his debut against Cambridge in the Capital One Cup.
The former Dundee United defender suffered the blow when colliding with goalkeeper Colin Doyle and had to be brought off after 38 minutes at St Andrews.
"Gavin has had a scan and it's not very positive," said Blues boss Lee Clark.
"He's done some damage to his posterior cruciate ligament, so we have to get that assessed by a surgeon but it's not looking too good at the moment. I expect us to be without Gavin for a good period of time."