David Denton is set to miss Scotland's Autumn Tests after suffering a serious hamstring injury in Bath's trouncing of Newcastle Falcons on Saturday, while Wales international Taulupe Faletau faces six to eight weeks on the sidelines.
Faletau has suffered medial ligament damage in his left knee, but is not expected to require surgery. However, the prognosis for Denton is much worse.
Bath director of rugby Todd Blackadder said: "Dave Denton could be four months. He's got to have surgery.
"It's his hamstring that's actually been torn off the bone, so really serious."
The lengthy lay-off for Denton could lead to former Bath star Leroy Houston making a swift return to The Rec on a short-term deal.
Houston left Bath for Queensland Reds earlier this year in a bid to gain international honours, but has yet to be capped.
"We've been scouring the earth trying to find a replacement. It could be Leroy, but we've got to get through a couple of things first," explained Blackadder.
"He was pretty special here. We've still got a few hurdles to jump getting his release, but I think it's going to happen, which would be great.
"It would be to bridge a short-term gap."