Nalaga pounced after just 17 seconds for the first of his two tries that secured victory at Parc Y Scarlets. The power of the French scrum also proved decisive after winning a penalty try while replacement Fritz Lee stepped off the bench to score.

The result means Clermont are sure to end round 4 at least three points clear at the top of the pool while the Scarlets can now only realistically aim for second place and a place in the Amlin Challenge Cup quarters.

Clermont were unbeaten in five previous meetings with Scarlets and could not have got off to a better start when Josh Turnbull lost possession from the kick-off and Nalaga, who had scored twice in the home win the previous weekend, won the foot race for Thierry Lacrampe’s kick.

But the Scarlets recovered from what could have proved a knock-out blow and led 13-10 at half-time. Clermont lost their talismanic captain Aurelien Rougerie to the sin-bin for punching and Rhys Priestland kicked the resulting penalty.

But the Wales outside half launched a counter-attack that made sure Scarlets gained even more from the 10 minute spell. Priestland ran a penalty from his own 22-yard line, Scott Williams provided the thrust though it needed Liam Williams to scoop possession off the deck for Priestland to release Maule.

Priestland converted and added a second penalty before Mike Delany halved their lead on the stroke of half-time. Brock James replaced Delany but missed his first two attempts at goal.

The game turned on 60 minutes after referee Wayne Barnes awarded a penalty try following a series of scrums close to the Scarlets line. Flanker Lee then crossed seven minutes later after Nathan Hines charged down Williams’ kick before Clermont’s scrum set up Nalaga’s second for the bonus point seven minutes from time.