Brentford skipper Kevin O'Connor faces an ankle operation which will rule the midfielder out for six months.
The 30-year-old suffered the injury in Tuesday night's 1-0 win at Portsmouth, and scans have revealed ligament damage, which requires surgery to repair.
The Bees' head of medical staff Neil Greig told the club's official website: "On Tuesday night against Portsmouth club captain Kevin O'Connor sustained a significant ankle and lower leg injury when falling awkwardly in a tackle, leading to him being stretchered from the field.
"Following scan investigations and consultation with a leading orthopaedic specialist, it has been established that Kevin will need to undergo surgery to repair the damage he has sustained.
"Kevin will undergo this surgery on Tuesday and then begin, what is anticipated to be, a six-month period of rehabilitation.
"Having worked closely with Kevin through his rehabilitation from long-term injury last season, I have absolute belief that he will return from this disappointing setback to play a key role for us. Kevin demonstrates a first-class attitude to recovery and we will offer him every support in order for him to complete his recovery."