Brive (10) 17
Tries: Bonrepaux, Agulla, Cook Con: Orquera
Scarlets (10) 20
Tries: Welch, Stoddart Cons: S Jones 2 Pens: S Jones 2
Stephen Jones' 63rd-minute penalty proved decisive in Brive
The Scarlets claimed a place in the Amlin Challenge Cup quarter-finals with a second successive fight-back win, this time at Brive.
Their hopes of a Heineken Cup knock-out spot went as Northampton took a losing bonus point at Munster on Friday.
But the Scarlets' triumph at winless Brive kept their European season alive.
Damian Welch and Morgan Stoddart scored Scarlets tries and fly-half Stephen Jones kicked 10 points, including the decisive 63rd-minute penalty.
They travelled to Brive on the back of a daring comeback win over London Irish at Parc y Scarlets last weekend, winning 31-22, and continued their bold progress with a battling win.
Brive, led by ex-Scarlet Alix Popham, made seven changes for their final Heineken Cup tie of the season, including moving England hooker Steve Thompson to number eight.
The hosts side went ahead in the 18th minute when Andy Goode kicked for the corner and, after securing line-out ball, hooker Jean-Philippe Bonrepaux burrowed over.
Brive's bright start continued when Argentine full-back Horacio Agulla kept Sean Lamont at bay to score.
Jones hit back with a long-range penalty on 28 minutes before Heineken Cup debutant lock Damien Welch burst clear to go over.
Martin Roberts, Jonathan Davies and Andrew Fenby combined to give Welch his chance.
Jones converted and the scores were tied 10-10 at the interval.
The Scarlets revival continued after the break when they took the lead for the first time.
Full-back Daniel Evans counter-attacked with a blistering 50-metre run and his off-load found Davies, the Wales centre, who took the visitors further forward.
With extra numbers to his right-hand side, Jones spotted Brive lock Retief Uys on the wing and capitalised with a perfectly-weighted grubber kick which Stoddart eagerly chased to score.
Jones converted, but the visitors pressed the self-destruct button in the 55th minute as flanker Josh Turnbull was sent to the sin-bin by referee Peter Fitzgibbon for foul play.
Within two minutes the hosts took advantage with a third try.
Replacement scrum-half Shaun Perry fed Riki Flutey and the England centre's deft pass provided midfield partner Ronnie Cooke with the simplest of scores under the posts.
Luciano Orquera converted before Lou Reed became the second Scarlets player to be sent to the sin-bin
But Jones had the final say with a long-range penalty to pass 800 tournament points.
Scarlets fly-half Stephen Jones:
"It wasn't pretty at times but we stuck in there and showed great character.
"It was a great effort from such a young squad. Everyone worked really hard in defence, especially when we went down to 14 men for 20 minutes.
"Brive are a very dangerous side with a big squad and we knew it would be a big ask to come here - we're delighted to get the win.
"We look forward to whoever we come up against in the quarter-finals."
Brive skipper Alix Popham:
"We had chances to be further ahead in the first half.
"We turned down kicks in front of goal as we wanted to go for tries.
"We could not get any further in this competition. It was a quick game and both sides like to play rugby.
"We're disappointed to lose but the Scarlets have a very good group of young players coming through."
Brive: Spedding; Agulla, Cooke, Flutey, Bianco; Goode, Pejoine; Henn, Bonrepaux, Toderasc, Dubarry, Uys, Popham, Domingo, Thompson.
Replacements: Orquera for Goode (55), Idieder for Henn (56), Kinchagishvili for Toderasc (56), Short for Uys (52), Azoulai for Popham (52).
Not Used: Ribes, Perry, Palisson.
Scarlets: Evans; Stoddart, Lamont, J Davies, Fenby; S Jones, Roberts; I Thomas, Owen, Manu, Welch, Day, McCusker, Turnbull, Lyons.
Replacements: L Williams for Stoddart (72), John for I Thomas (55), Rees for Owen (55), R Thomas for Manu (71), Reed for Day (56), Edwards for McCusker (57).
Not Used: Priestland, Maule.
Sin Bin: Turnbull (57), Reed (69).
Ref: Peter Fitzgibbon (Ireland).