Derby defender Martin Albrechtsen is facing a month on the sidelines after undergoing a hernia operation.
The Danish centre-half missed the 2-1 win at Norwich on Saturday with a groin problem and has gone under the knife in an attempt to resolve the issue.
His impending absence over the coming weeks will come as a major blow to the Rams, as the club have begun to rediscover the winning habit of late.
"Martin has had the operation this morning (Tuesday) that will probably keep him out for a minimum of four weeks, which is disappointing for us," Derby boss Paul Jewell told the club's official website.
"There is no good time in this league to have an operation because by the time the next games come around we are back in the Saturday-Tuesday cycle again.
"Martin is going to miss a fair sprinkling of games. He has had this groin problem so the surgeon wanted the operation done as quickly as possible."
Jewell admits he may now be forced to delve into the loan market after seeing his other first-choice centre-half, Dean Leacock, ruled out of the club's next outing against Plymouth after collecting five yellow cards.
"It's a major blow that Dean is suspended for the next game and we are all of a sudden down to three centre-halves at the moment," he added.
"Two (Lewin Nyatanga and Claude Davis) are on international duty so we have got to keep our fingers crossed that they come back in one piece.
"It is not ideal but that is what a season in the Championship is about - dealing with injuries, dealing with suspensions, and you know you are going to get tested.
"Maybe we will have a look at the loan market."