Morgan Parra's participation in the Six Nations is in question after he injured his knee against South Africa on Saturday.
The France scrum-half could miss three months with a ruptured posterior cruciate ligament and is almost certain not to be available for their first two matches in the tournament against Italy and Wales in early February.
Parra was hurt towards the end of France's 19-10 defeat by the Springboks in Paris and his club Clermont confirmed the severity of the injury on Monday.
"He doesn't need surgery," a statement on Clermont's website reported. "His comeback is envisaged from the middle of February."
Parra played in all three of France's autumn internationals and scored 16 points in their 38-18 win over Tonga.
Should his recovery go according to schedule, Parra's return could coincide with France taking on England at Twickenham on February 23. They then take on Ireland in Dublin on March 9 and Scotland in Paris seven days later.