Ospreys flanker Tom Smith needs to have surgery to repair the knee injury he suffered in the 44-10 win over Edinburgh in September.
The 27-year-old met with a specialist consultant in London and now faces a lengthy spell on the sidelines.
"Tom suffered a complex multi-ligament injury to his knee that will ultimately require surgery," Ospreys head physio Chris Towers said.
"The surgery will then be followed by a lengthy... rehabilitation process."
The injury is another blow for Smith, who has had to battle back from a umber of injuries including a groin problem that kept him out for most of last season.