Clermont forwards boss Franck Azema admits his charges face a real test of their title credentials when they take on Castres at Pierre Antoine on Friday.
Les Jaunards will seek to ride out a raft of injuries as they travel to Castres, who are unbeaten at home this season, in what will be a tough game.
Castres have scored over 30 points at home in each game this term and also possess a home hoodoo over Clermont that goes back 36 years.
"We're looking at this match as a real test," Azema said ahead of their daunting Top 14 trip.
"Castres are an outfit used to play-offs.
"They've been able to build thanks to a real stability among their backroom staff and playing personnel.
"Even if some players have left and others come in, they've managed a smooth continuity and know how to adapt themselves and bring the best out of the squad."
Azema added that a run-out against Castres would be ideal timing ahead of the Heineken Cup, in which they've been drawn in a group alongside Leinster, Exeter and the Scarlets.
"Of course it's an excellent way of preparing for our clash against Scarlets," Azema said of their October 13 match-up at home against the Welsh region.
"We'll have a very tough team up against us who will pose us problems. It'll be up to us to find solutions. It will also prepare us for the level of combat that awaits us in a complicated European pool."
Castres hooker Brice Mach, making his comeback after treatment for thyroid cancer, said remaining unbeaten at home had been one of the squad's targets at the start of the season.
"The team wants to act like the head of the household," Mach said of Castres, who travel to Ulster for their opening European Cup match on October 12, with Glasgow and Northampton making up their group.
"These matches give us confidence and we must approach them very seriously.
"Up until now, it's smiled on us because we have put in all the necessary ingredients. Come Friday, we'll have to be vigilant and snuff out the opponents from the off."