Derby are waiting to discover the extent of Kris Commons' latest hamstring injury.
The Scotland international forward, who was out for more than two months earlier this season with hamstring and calf problems, was forced off midway through the first half of Saturday's ill-tempered home defeat to Swansea.
"He has been one of our match-winners in the last couple of weeks. Hopefully, he won't be out too long," said manager Nigel Clough.
He added: "We will get the usual scans done and after two or three weeks we would hope to get him back but it is too early to tell.
"We don't want it to be another five or six-week absence because that effectively takes you into the last month of the season."
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