Derby defender Russell Anderson is facing up to three months on the sidelines with a hamstring injury.
He suffered the setback in a 3-0 defeat to Cardiff at Pride Park last Wednesday.
The 33-year-old has been beset by injury problems since joining the Rams in January 2010 and had hoped those troubles were behind him.
Having returned to full fitness following a groin complaint sustained at the start of last season, the Scotland international had been covering at right-back for the stricken John Brayford.
He has, however, picked up another knock and is set to see out 2011 on the treatment table.
"Unfortunately Russell is going to be out for a little while and we are all gutted for him," Rams boss Nigel Clough told the club's official website.
"It is quite serious. He has had no luck at all in the last year or so.
"It is a devastating blow for him. He is a great professional and he has had such a bad run of injuries, a bit like Steven Davies.
"We all feel for Russell and he is likely to be out for two to three months."