Ospreys centre Ashley Beck is expected to be out for at least eight months after suffering a serious knee injury.
The 25-year-old, who has seven Wales caps, will have surgery later this week to repair a ruptured anterior cruciate ligament.
Beck suffered the injury in Ospreys' Pro12 loss to Ulster on the opening weekend of the season.
He had only recently returned to fitness after breaking a bone in his foot last February.
"All being well he will undergo surgery before the end of the week," said Ospreys medical performance manager Chris Towers.
"His rehab will then begin immediately. For this kind of injury we are looking at an estimated eight month recovery period for him to be back to full fitness."