Exeter will be without Will Chudley for up to two months after the scrum-half tore his pectoral muscle.
Chudley missed Exeter's 31-19 win over Ulster on Sunday and now looks set for an extended time on the sidelines.
"He'll be out for a little while," head coach Rob Baxter told the Express and Echo.
"We are still fully assessing the extent of the injury but we won't suddenly see him on the pitch against Clermont on Saturday.
"It is a chest injury – it looks like a pectoral tear. At this stage it is a little bit early to say how long he'll be out for but you are probably looking at a couple of months at the very least."
Chudley's injury does at least open the door for others at Sandy Park. Dave Lewis, who is widely expected to leave over the off-season, performed well in Sunday's Pool Five clash, with Stu Townsend coming on in the final stages and holding his own.
Jack Maunder has also impressed, while Exeter also have Niko Matawalu recovering from a hand injury.
"It means Stu and Jack are going to have a big work load over the next couple of months and Dave Lewis has the opportunity to play plenty of rugby as well," said Baxter.