Derby are waiting to discover the extent of the hamstring injury Alberto Bueno suffered against Burnley.
The 22-year-old Spanish forward was forced off after only 14 minutes of the 2-1 defeat at Turf Moor on Saturday evening and will be assessed over the coming days.
"We are not certain at this stage how bad it is we will know more in the next 24 or 48 hours," said manager Nigel Clough.
"Getting him off straight away will have helped but hamstrings are very rarely only a week, so we are probably looking towards the Christmas period before he is available again.
"I don't think Alberto has ever played in conditions as cold as it was at Burnley, coming from Spain, and possibly that had something to do with it."
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