Paul Jewell has admitted that Andy Griffin may not be fit for Derby's clash with Newcastle on Sunday.
The versatile defender suffered a calf injury in the 1-0 defeat to Middlesbrough at the weekend and had to be substituted after just half an hour.
Jewell also has fitness concerns over midfielder Stephen Pearson and striker Robert Earnshaw ahead of the trip to St James' Park.
"Andy Griffin has a calf injury and it looks like he could be a doubt for the weekend," Jewell told the club's official website.
"Stephen Pearson is a bang on the thigh that he has been carrying for a couple of weeks and he is also a little concern.
"Robert Earnshaw also felt a groin in training on Monday."
Jewell admits his resources are being stretched to the limit and is looking forward to bringing in new players next month.
He said: "We have five players currently away on loan so we are down to the bare bones and need help during the January window."