Clermont's entire rugby union squad were drug tested on Thursday morning before the French Top 14 side meet English club Leicester in the European Cup quarter-finals on Saturday.
The mass testing was carried out before the morning training session and disrupted the entire day's schedule, coach Vern Cotter said.
"Commissioned by the IRB (the sport's governing body), testers from the AFLD (French anti-doping agency) arrived at the premises of ASM Clermont Auvergne, this morning," the club from central France said earlier.
"We have to adapt," said the New Zealand coach cryptically, as captain Aurelien Rougerie expressed his anger.
"I'm not sure the IRB helped us to prepare for the match correctly," said Rougerie. "I hope that Leicester are in the same boat."
"It's a bit annoying but not really bad. They arrived, the big brigade, four to test 40 guys. It's irritating."
Prop Thomas Domingo added: "There were already (tests) last weekend after the Brive match. Maybe they'll leave us alone now. But we mustn't let that bother us, we have something more important in two days."
Last year's European Cup finalists Clermont host Leicester on Saturday at their Marcel-Michelin stadium where the club have won their last 74 matches.