France's veteran winger Vincent Clerc could miss this year's Six Nations after he suffered a thigh injury on Friday.
The 31-year-old, who is the Heineken Cup's all-time leading try scorer, pulled up in the latter stages of Toulouse's 19-14 win over Biarritz and said afterwards that he feared a muscle pull.
France have already had centre Gael Fickou and full-back Brice Dulin ruled out of next month's tournament.
They begin their Six Nations campaign against Italy in Rome on Sunday, February 3.
