Injured Worcester Warriors forwards Ryan Bower and flanker Zac Xiourouppa are both expected to miss the rest of the season.
Bower tore his Achilles tendon in Sunday's 34-22 Premiership Cup defeat at Saracens, which also saw the loss of Xiourouppa, who is on dual registration terms with Cornish Pirates.
He suffered an anterior cruciate ligament knee injury at Allianz Park.
"Ryan's got to be operated on," said director of rugby Alan Solomons.
"I'd be very surprised if he plays again this season. It's that sort of injury. And Zac has done his ACL, his cruciate ligament."
Warriors also lost young lock Andrew Kitchener with concussion but he is going through the return-to-play protocol and may be fit for the weekend.
After a five-week break because of two games in the European Challenge Cup and three in the Premiership Cup, Warriors return to league action at Bath on Saturday.
Flanker Marco Mama is unlikely to play as he is still struggling with a hamstring injury, but centre Ryan Mills and lock Pierce Phillips are both fit again and available for selection.
Worcester are again without three players on England duty.
Lions centre Ben Te'o, uncapped prop Nick Schonert and 19-year-old flanker Ted Hill, as an apprentice selection, are all part of Eddie Jones' 30-man squad for Saturday's international against Japan at Twickenham.