Nathan Tyson is a major doubt for Derby's opening Championship fixture against Carling Cup holders Birmingham at Pride Park.
The forward, a summer signing from East Midlands rivals Nottingham Forest, was forced off after 36 minutes of the Rams' final pre-season friendly against Aston Villa on Wednesday night with a groin problem.
Substitute Conor Doyle also limped out of the game following a knock on the shin.
Derby were already without Gareth Roberts, Jamie Ward, Stephen Pearson, Shaun Barker, Paul Green and Jake Buxton against Villa.
Ward and Pearson could be available for Saturday but Roberts is rated 50-50, so latest signing Kevin Kilbane may make his Rams debut at left-back.
James Bailey is another option to fill in for Roberts after returning from a groin injury against Villa, although he could play in his more accustomed midfield role.
Chris Hughton faces an attacking dilemma for his first match in charge of Birmingham.
Summer signing Marlon King (knee), Nikola Zigic (groin) and Cameron Jerome (ankle) - who was earlier this week the subject of a failed bid from Fulham - are all unavailable for the trip to Pride Park.
That means Hughton could be forced to adopt a 4-5-1 system, with new-boy Adam Rooney up front on his own.
Rooney will no doubt need effective service from out wide and that could come in the form of emerging youngster Nathan Redmond, who may make his league debut. Summer arrival Chris Burke and Chile international Jean Beausejour are also competing to start.
Scott Dann and Liam Ridgewell should both start in defence despite continued speculation over their futures.
New recruits Boaz Myhill, Steven Caldwell, Jonathan Spector and Morgaro Gomis are also aiming to make their bows.
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