Derby defender Shaun Barker has finally had surgery on a knee problem that he has been carrying for some time.
The 28-year-old had the operation on Thursday, having continued playing until the Rams' Championship survival was beyond doubt.
Boss Nigel Clough told the club website: "The operation went well, although a bit more damage was discovered than we originally expected.
"We're not putting a timeframe on when Shaun will be back."
Barker will now sit out the last two games of the season, having missed only one other game this term.
"We look forward to seeing him in action next season," added Clough.