Ospreys will be without wing Jeff Hassler for the remainder of the season due to an Achilles injury.
The Canada international was taken off on a stretcher in the first half of the Pro12 46-24 victory over Cardiff Blues last Friday.
Hassler, who has featured in all six league matches for Ospreys this season, will not require an operation but the issue could rule him out for up to nine months.
Ospreys medical performance manager Chris Towers said in a statement: "Jeff sustained an Achilles tendon injury on Friday night and investigations over the weekend and discussions with specialists have confirmed the injury doesn't require surgery.
"However, he will be out of action for a prolonged period, with an initial prognosis of six to nine months."
Back-rower Tyler Ardron could also be facing two months on the sidelines after undergoing surgery on a dislocated thumb.
"Tyler suffered a dislocated thumb which required a small surgical procedure at the end of last week. His recovery will keep him out for up to eight weeks," added Towers.