Derby County skipper Shaun Barker faces a lengthy spell on the sidelines with damaged knee ligaments sustained in Tuesday night's win over Nottingham Forest.
Barker has made 105 appearances for the Rams since joining from Blackpool in 2009, but the towering defender could face months out following the injury.
While the club's medical staff refused to a put timescale on Barker's recovery, the prognosis does not look good for the former Rotherham player.
Derby's head physio Neil Sullivan told the club's official website: "Unfortunately for Shaun, he has suffered ligament damage.
"At this moment in time it's very difficult to put a timeframe on things and that's probably not fair on Shaun either and we'll get a clearer indication once Shaun has undergone surgery."
Derby manager Nigel Clough was quick to pay tribute to his captain and said the club will offer him all the support he needs.
Clough said: "Shaun has been a real leader for us since returning from injury in November and he played a major role in our rise up the table during December and January. It was no coincidence that our run of clean sheets came following his return to full fitness.
"Everyone will be rallying round Shaun to help him through his rehabilitation programme. He will remain our captain and while he won't be able to influence things on the field for a while, he still has a massive role to play off the field."