Clermont's Wales international fullback Lee Byrne looks set for a long period on the sidelines after breaking a bone in his back during Saturday's 28-21 European Cup victory over two-time defending champions Leinster.
Clermont, who lead Leinster by eight points in their pool with two games remaining, said that they would know more about the length of time he would be absent once the 32-year-old undergoes further tests.
"He suffered a broken bone in his fifth vertebra," announced the club on their website.
"The length of his unavailability will be ascertained in the coming days by complementary examinations but we will not be seeing Lee Byrne again until at least the beginning of 2013."
Clermont, yet to win the European Cup and who won only their first domestic league title in 2009, have several other injury doubts ahead of their Top 14 clash at Bordeaux-Begles on Friday.
Veteran Canadian lock Jamie Cudmore, is suffering from a badly bruised right shoulder, Fijian wing Napolioni Nalaga has a painful knee and captain and centre Aurelien Rougerie, who has a painful pelvis.
Clermont are presently third in the Top 14 table after 12 matches, seven points behind leaders Toulon, while Bordeaux are struggling, third from bottom and just a point above the relegation places.