Derby forward Kris Commons is set for at least a month on the sidelines after receiving the results of a scan on his injured hamstring.
Commons was replaced early on during the 1-0 defeat to Swansea last weekend and the scan has revealed a nine centimetre tear in his hamstring.
Manager Nigel Clough told the club's official website: "The scan has confirmed what we feared and it does mean we will be without Kris for at least a month."
Clough added: "It is undoubtedly a blow because he has been excellent in recent weeks. He will need to show the same determination and commitment to come back from this latest setback."
Copyright (c) PA Sport 2009, All Rights Reserved.