Alun Wyn Jones has been ruled out for up to 16 weeks after picking up a shoulder injury at the weekend.
The Ospreys captain needs surgery to repair ligament damage sustained in Wales's loss to Argentina at the weekend.
Ospreys head physio Chris Towers told the club's website: "After carefully reviewing the scans and discussing the best management of the injury with specialists, the recommendation was made for Alun Wyn to undergo surgery in order to give him the best chance of making a full recovery.
"He is due to undergo the surgery at the end of this week, and we will be looking at a 12-16 week rehab process post-op to get him back on the field."
The lock will miss the remainder of Wales's Autumn International fixtures against Samoa, New Zealand and Australia, as well as the rest of the Heineken Cup pool stages.
