Italy skipper Sergio Parisse will miss the Six Nations after undergoing knee surgery.
The Stade Francais flanker had an operation to repair the anterior cruciate ligament in his right knee and is expected to be sidelined for six months.
He damaged the joint in training prior to the Azzurri's 24-6 victory over Samoa on November 28.
"The surgery has gone well and the player will be released from hospital on Tuesday," Italy's national team doctor Gianluca Melegati said in a statement.
"Parisse will be able to walk with the help of crutches and will immediately begin physiotherapy.
"The time of recovery is estimated at 180 days."