Bristol centre Semi Radradra will undergo knee surgery on Monday and is likely to be out for four months.
The Fijian, 29, originally sustained the injury while representing his country in the rugby sevens semi-finals at the Tokyo Olympics in August.
He did not feature as Bristol beat Bath 25-20 on Friday to claim their first Premiership win of the season.
“The good news is that the surgery will fix it 100%,” Bristol rugby director Pat Lam said.
Radradra signed a three-year deal with Bristol in 2019 after turning down a return to rugby league.
“We are looking at him having surgery on Monday, and he will end up with probably 16 weeks out,” Lam added.
“At the end of the day, there is a lot of rugby to be played when he gets back.”