|Toulon (18) 28|
|Tries: Giteau, Mermoz, Armitage Cons: Halfpenny 2 Pens: Halfpenny 3|
|Scarlets (13) 18|
|Tries: Barclay, Phillips Con: Priestland Pens: Priestland 2|
Toulon's bid for a historic third successive European crown began with a scrappy win against battling Scarlets.
Matt Giteau's mesmerising opening try for the hosts was cancelled out by John Barclay rewarding a team effort.
Maxime Mermoz scored from the restart and English exile Steffon Armitage put the outcome beyond doubt.
Scarlets, whose former chief Stuart Gallacher died on Sunday, showed determination with a late try through Kristian Phillips, but Toulon held on.
Wales and British and Irish Lions star Leigh Halfpenny kicked his first points for Toulon to open the scoring with a penalty.
And he went on to add two conversions and two more penalties in the cauldron on the Mediterranean.
Wales fly-half contender Rhys Priestland converted Barclay's try for Scarlets and added two penalties.
But the game itself centred on the frenetic efforts of all concerned and the litany of errors that resulted.
Time and again Toulon created chances only to waste them with inaccurate finishing touches.
Visiting number eight Rory Pitman's high tackle on David Smith led to a yellow card after five minutes.
The hosts then went ahead through Halfpenny's boot but fly-half Priestland levelled for the visitors before Giteau's opening try.
Former Wallaby Giteau took advantage of a Scarlets defence that was depleted by players needing treatment around the field.
The home fly-half's interplay on the way to the line was spectacular. But the hosts did not have it all their own way in the opening period.
Scarlets' attacking intent brought a stunning reward. Scotland flanker Barclay finished off a multi-phase attack, taking scrum-half Aled Davies' final pass to dive over.
Priestland put Wayne Pivac's side ahead for the first and only time with the conversion, but it was short-lived.
Moments later the visitors were under their own posts after centre Mermoz charged down skipper Scott Williams' laboured clearance to hack on and score.
That left Priestland and Halfpenny to exchange another penalty each before the break.
And while the visitors' hopes were maintained by their own endeavours and Toulon's generosity in spurning numerous chances, hopes of a stunning win were dashed.
Scarlets hooker Emyr Phillips was sin-binned in the 53rd minute for killing one Toulon attack after wing David Smith was hauled down short.
Halfpenny kicked the first points of the second period with 15 minutes remaining and it was to Scarlets' credit that it took Toulon until 10 minutes from the end to provide the platform for Armitage to touch down.
At the other end Halfpenny produced the tackle of the match to prevent wing Harry Robinson from scoring.
But the former Cardiff Blue and his team-mates were powerless to prevent Kristian Phillips' pace taking him to the line with the last move of the game.
Scarlets captain Scott Williams: "Everyone wrote us off before the game so we just built on that and we tried to prove everyone wrong and I think we proved that we can compete with these teams.
"And hopefully a couple of people's opinions of us might change now."
Toulon full-back Leigh Halfpenny: "We got the win. That was the main thing. It was tough. Credit to the Scarlets - they brought a huge battle.
"It was frustrating - we created opportunities, we had chances. I think we left a few tries out there.
"At half-time it was touch and go, but with the character of the boys, we dug deep."
Toulon: Halfpenny; D Smith, Bastareaud, Mermoz, Habana; Giteau, Tillous-Borde; Chiocci, Orioli, Hayman, Botha, Williams, J Smith, Fernandez Lobbe, S Armitage.
Replacements: O'Connor for D Smith (73), Wulf for Bastareaud (70), Claassens for Tillous-Borde (67).
Not Used: Guirado, Menini, Chilachava, Masoe.
Scarlets: L Williams; Robinson, M Tagicakibau, S Williams, K Phillips; Priestland, A Davies; R Evans, E Phillips, Lee, Ball, Snyman, A Shingler, Barclay, Pitman.
Replacements: S Shingler for Tagicakibau (20), R Williams for A Davies (59), Myhill for A Shingler (59), J. Davies for Barclay (73).
Not Used: John, R Jones, Earle, J Williams.
Sin Bin: Pitman (7), E Phillips (54).
Ref: JP Doyle (RFU).