Clermont took control of Heineken Cup Pool 4 on Saturday thanks to a 31-13, bonus-point victory over the Scarlets.
Napolioni Nalaga's brace, a score from replacement Fritz Lee and a penalty try added to 10 points from Mike Delaney and four from Brock James at a rain-soaked Parc y Scarlets.
The hosts were well in the game at heading into the final quarter, despite falling behind to a Nalaga try just 20 seconds in, with Gareth Maule's try giving them hope.
Clermont were eventually able to dominate, though they were given a good test in Llanelli.
Scarlets were facing a tough test against last year's beaten finalists, and were breached immediately by Fijian Nalaga, who crossed to make the Welsh side's task even more tricky.
Heavy wind and rain made kicking difficult, with the visitors' fly-half Mike Delaney missing two consecutive penalties, despite nailing an earlier conversion. Scarlets capitalised on a man advantage midway through the first half, when Clermont had captain Aurelien Rougerie sent to the sin bin, as Rhys Priestland took aim with a successful penalty.
The home crowd were then treated to a superb team try, as Gareth Maule rounded off a superb move which included a significant contribution from Priestland. And it was their number 10 who extended the lead to 10-7.
Clermont were rattled by Scarlet's resurgence, a penalty apiece for Priestland and Delaney meaning Vern Cotter's side trailed 13-10 at the break.
Brock James was introduced for the second period, and suffered with his place kicking, missing two consecutive three-point attempts.
A sustained period of scrums on their own line looked to be taking its toll on Scarlets, with a penalty try eventually being awarded as their pack creaked backwards, meaning they trailed 13-17.
The game was finally put to bed when Fritz Lee was awarded Clermont's third try, after much deliberation from the TMO.
Nalaga then secured the bonus point with a powerful run, which was again checked upstairs before being awarded.
Pens: Priestland 2
Tries: Nalaga 2, Penalty try, Lee
Cons: Delany, James 2
Yellow card: Rougerie
Scarlets: 15 Liam Williams, 14 Nick Reynolds, 13 Gareth Maule, 12 Scott Williams, 11 Jordan Williams, 10 Rhys Priestland, 9 Gareth Davies, 8 Rob McCusker, 7 John Barclay, 6 Josh Turnbull, 5 George Earle, 4 Jake Ball, 3 Samson Lee, 2 Ken Owens, 1 Phil John
Replacements: 16 Emyr Phillips, 17 Rob Evans, 18 Rhodri Jones, 19 Richard Kelly, 20 Jo Snyman, 21 Rhodri Williams, 22 Aled Thomas, 23 Adam Warren.
Clermont: 15 Jean-Marcellin Buttin, 14 Sitiveni Sivivatu, 13 Aurélien Rougerie (c), 12 Regan King, 11 Napolioni Nalaga, 10 Mike Delany, 9 Thierry Lacrampe, 8 Damien Chouly, 7 Julien Bardy, 6 Julien Bonnaire, 5 Julien Pierre, 4 Jamie Cudmore, 3 Clément Ric, 2 Benjamin Kayser, 1 Thomas Domingo
Replacements: 16 Ti'i Paulo, 17 Raphael Chaume, 18 Daniel Kotze, 19 Nathan Hines, 20 Fritz Lee, 21 Ludovic Radoslavjevic , 22 Brock James, 23 Noa Nakaitaci.
Venue: Parc y Scarlets
Referee: Wayne Barnes (England)
Assistant referees: Matthew Carley, Nigel Carrick (both England)
TMO: David Grashoff (England)