Queens Park Rangers have confirmed that Martin Rowlands has been ruled out for the remainder of the season.
The Rangers skipper damaged anterior cruciate ligaments during Saturday's 2-0 victory over Derby.
He was forced from the field after only 11 minutes at Pride Park, tumbling under an innocuous looking challenge from Miles Addison.
Rowlands then underwent scans on Monday, with the severity of the injury having now been revealed.
"Unfortunately, our worst fears have been confirmed," Rangers' head physio Paul Hunter told the club's official website.
"Martin has seen a specialist and he will be back in hospital for surgery on Wednesday afternoon.
"Obviously, we are all desperately disappointed, but being the positive character and strong man that he is, we are confident Martin will bounce back from this setback and approach his rehabilitation in a positive manner."
QPR boss Paulo Sousa added: "Martin is our captain and our leader - he epitomises everything we are about.
"We have lost him as a player, but we will not lose him as a personality, because he is a huge character around the club and I will continue to involve him as much as possible.
"He is a player we all hold in extremely high regard and we will be doing everything we can to get him back to full fitness as soon as possible."