Sparkling Fijian wing Alivereti Raka is out for the rest of the season with a torn cruciate knee ligament, his club Clermont said on Monday.
The 25-year-old flyer was injured during Sunday's 24-21 win over holders Saracens in the European Champions Cup.
The news will come as a massive blow to injury-ravaged French champions Clermont, who also saw talented young French centre Damian Penaud fracture a bone in his foot against Sarries, which will see him miss "around" three months.
Clermont, whose poor form in the French Top 14 has been in stark contrast to their scintillating European performances, already have first choice fly-half Camille Lopez, Fiji-born French international wing Noa Nakaitaci and former All Black Luke McAlister on the sidelines.
"We have a huge amount of injuries and we've already signed the maximum number of two injury cover players," a Clermont spokesperson told AFP.
"The only possible solution would be to sign an extra player, but that's up to the managers."
Clermont have won all four European matches this season to top Pool 2 by five points from Ospreys with two matches to play.
But domestically they are down in ninth in the Top 14 standings after 12 matches.
Penaud's injury means he will also likely miss the Six Nations. The 21-year-old has five caps, all won this year.