Brentford defender Alan McCormack is expected to be out for three months with an ankle injury.
The 30-year-old will have surgery on Monday to repair ligament damage suffered in the 3-1 defeat at Bolton.
"Alan has sustained a nasty and unusual ankle ligament injury," Brentford head of medical Neil Greig said.
"The opinion of the leading ankle consultant in the country has been sought and early surgical repair is the most proactive course of action."
Right-back McCormack, who signed a new two-year with the Bees in September, has scored one goal in 14 appearances for the Championship club this season.
"The medical and conditioning staff will give Alan every support in the coming months in order to ensure his safe return to action as swiftly as possible," added Greig.