Worcester Warriors full-back Melani Nanai could miss the rest of the season after injuring his knee against Saracens on 26 December.
It is feared injury-hit Nanai has suffered another significant setback.
“The early indications are that is an anterior cruciate ligament injury and it could be season ending,” head coach Jonathan Thomas said.
“You have to feel for him because he has already had a number of injury challenges to overcome.”
Nanai missed the bulk of last season because of a torn hamstring that required surgery – his second major absence since joining Warriors in 2019, after needing a shoulder operation in February 2020 that ruled him out of the remainder of that campaign.
Meanwhile, Thomas is confident Sunday’s Premiership game against bottom club Bath at The Rec will go ahead despite Bath’s ongoing issues with Covid.
The West Country side had to cancel a Premiership Rugby Cup game against Exeter Chiefs on 29 December and their Premiership meeting with London Irish on 3 January due to cases of the virus in the squad, together with existing injury problems.
“We are in reasonable shape with Covid – this week we decided to PCR test all the players and playing staff on Monday in addition to their usual lateral flow tests,” added Thomas.
“We didn’t need to do that but we wanted to be vigilant with people coming back in having been away over Christmas and new year.”
Bath are yet to win in the league this season but have never lost to Warriors at home in the top flight.