Clermont full-back Lee Byrne suffered a broken bone in his fifth vertebrae against Leinster on Saturday.
Byrne is set to be out for some time and his participation in next year's Six Nations with Wales is now in doubt.
The 32-year old is set for further tests to determine how long he will be on the sidelines.
"He suffered a broken bone in his fifth vertebra," the club said 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."