Wales international scrum-half Rhys Webb is to undergo surgery after suffering a knee injury.
The Ospreys have confirmed that Webb sustained an injury to his anterior cruciate ligament during last Friday's RaboDirect PRO12 defeat against Leinster in Dublin.
He underwent an MRI scan earlier this week, which confirmed the damage.
"The MRI scan report has confirmed what we suspected, which is that Rhys has sustained an injury to the anterior cruciate ligament," Ospreys head physiotherapist Chris Towers said.
"He will undergo reconstructive surgery at a date to be confirmed over the next few weeks, and is looking at a lengthy period of rehab after that."