Top 14 runners-up Castres will be without their star recruit Sitiveni Sivivatu for the start of the season because of a shoulder injury.
The former All Black winger only joined Castres this off-season, having spent three seasons with Clermont Auvergne but now faces three to four months on the sidelines.
Sivivatu was injured in Castres' final pre-season game with Brive, and having seen a specialist, he will need an operation on his shoulder.
It's a blow for Castres, who will also be without flanker Ibrahim Diarra for their season opener after he was suspended for one game because of a punch-up in a pre-season defeat to Brive.
Despite those early-season absences, Castres have sight their sights high, with skipper Rémi Talès eager to challenge both domestically and in Europe.
While they have been consistent contenders in the Top 14 having reached back-to-back finals, Castres have struggled in Europe in recent seasons, but France fly-half Talès is optimistic that things will change.
"We can't say that we are going to get back to the final again this year, but we really want to make sure that we finish in the top six and reach the play-offs," he told Rugbyrama.
"We saw last season that even finishing sixth, we weren't far off going all the way, so we want to make sure we're in the six.
"We also want to perform well in Europe, and try to get out of the group. It's a tough group again [Leinster, Harlequins and Wasps] but we're ambitious and want to do well in both competitions."