Derby ace Kris Commons faces a month on the sidelines after picking up a hamstring injury.
Commons was forced to limp off early on during Saturday's home defeat to Swansea and scans have revealed a tear to the attacker's hamstring.
Rams boss Nigel Clough admitted it was a major blow to lose Commons, who has been in fine form in recent weeks.
"The scan has confirmed what we feared and it does mean we will be without Kris for at least a month," Clough told the club's official website.
"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."