Scans have revealed that Michael Dawson has suffered a partially torn left ankle ligament.
The 25-year-old defender was forced off with the injury in last weekend's victory against Newcastle United and is expected to be sidelined for up to three weeks.
OTHER TEAM NEWS
Roman Pavlyuchenko has also been ruled out of this weekend's trip to Manchester United in the Barclays Premier League.
The striker is still suffering from the back injury that kept him out of last weekend's win against Newcastle, although scans have revealed no long-term damage.
Fellow frontman Fraizer Campbell is ineligible to face his parent club due to the terms of his loan deal from United.