Ospreys forward duo Tyler Ardron and Nicky Smith are set to miss eight weeks of rugby after they suffered knee and ankle injuries respectively.
Ardron suffered his second knee injury in recent months in Canada's Rugby World Cup game against France at Elland Road at the start of October.
"He underwent keyhole surgery last week before returning to the Ospreys and is looking at a best-case scenario of eight weeks before he will be able to return to playing," read a statement from the Welsh region on Tuesday.
The statement continued: "Nicky injured ankle ligaments during the Edinburgh game and, although surgical intervention was not needed, previous experience of this kind of injury suggests that he is likely to be out for six to eight weeks."
Ospreys travel to Italy to face Treviso in their PRO12 fixture this Saturday.