First half tries by forwards Mario Ledesma and Loic Jacquet handed the star-studded French side a lifeline as they wait nervously to see if Bourgoin can do them a favour by beating the Ospreys at the Stade Pierre Rajon today (Sun).
Last season's semi-finalists the Scarlets suffered their sixth successive defeat in the pool of death and their biggest ever margin of defeat at home in the tournameant was confirmed when Brock James scored Clermont's third try on 46 minutes before Anthony Floch scored tries either side of man of the match Elvis Vermeulen's score.
Clermont opened the try-scoring after just six minutes when Ledesma powered through a weak Scarlets' defence. The Argentinean hooker looked to have dropped the ball short but Irish official George Clancy consulted with the Television Match Official before signalling for the try.
Brock James converted to grant the visitors a comfortable lead. And Clermont doubled their advantage on 25 minutes when Julien Bonnaire won a line-out in the Scarlets' 22 before setting up second row Jacquet who steamrollered through the home defence.
The Scarlets introduced Alix Popham at the break in the hope of changing the course of the match but it had the opposite effect as James increased the lead on 43 minutes with a penalty. And any hopes of the hosts staging a second half fightback were well and truly killed off three minutes later when Brock James scored Clermont's third try; The Australian fly half dived on fullback Anthony Floch's kick through to seal the Scarlets' fate.
Matthew Rees was sin-binned for killing the ball and Samoan hooker Mahonri Schwalger came on for his debut. And Clermont used their numerical advantage immediately to gain the bonus-point when Floch touched down in the left corner.
The French side weren't finished there and will watch their television sets with huge interest as man of the match No.8 Vermeulen powered over for their fifth try with seven minutes remaining before Floch added his second and Clermont's sixth try in injury-time.