Italy and Bayonne fly-half Craig Gower has gone under the surgeon's knife today to repair damage to his anterior cruciate ligament.
The operation will rule the Australian-born play-maker out of action for between four and six months, which will mean he will miss the entire Six Nations and potentially the remainder of the Amlin Challenge Cup.
"His recovery time is estimated at 120 to 180 days," said an Italian Rugby Federation statement.
Bayonne currently lie third in pool one having won one and lost one of their first two fixtures, although Gower is yet to feature in the competition this year.
Gower's operation was performed by Prof. Herbert Schoenhuber at the Galeazzi Orthopaedic Institute with the Italian team doctors Roberto Pozzoni and Corrado Bait present. The club are awaiting further news on the success of the operation before officially confirming the expected length of Gower's absence.