Dwayne Peel and Gavin Evans lead the Scarlets celebrations
Ulster (11) 11
Pen: Wallace, Steinmetz
Scarlets (7) 35
Try: Popham, King, Stoddart, Peel, Thomas
Cons: Jones (5)
Llanelli Scarlets qualified for the Heineken Cup quarter-finals by claiming a superb win over Ulster at Ravenhill.
Tommy Bowe's try helped Ulster lead 8-0 but Alix Popham's touchdown cut the home team's lead to 11-7 at the break.
Scarlets withstood Ulster pressure after half-time and Regan King then snatched a second try for the visitors.
Morgan Stoddart's try ended the contest and Ulster's faint qualification hopes and Dwayne Peel and Gavin Thomas added further Scarlets touchdowns.
The match was played in appalling conditions with the windy conditions of the first half deteriorating into torrential rain in the second period.
Ulster, needing a bonus-point victory to keep their hopes alive, notched a early wind-assisted penalty with Ireland fly-half Paddy Wallace hitting the points after Deacon Manu's high tackle on Kieron Dawson.
However, the Scarlets regrouped to dominate possession for the next 15 minutes with young full-back Stoddart making a couple of darting breaks to put the Ulster defence under pressure.
Against the run of play, Ulster notched their try after a turnover in the 14th minute.
Ulster's Neil Best is grabbed by Simon Easterby
Scrum-half Kieran Campbell picked up possession and his kick behind the Scarlets defence enabled Bowe to slide over for the try despite Mark Jones' best efforts.
Wallace missed the conversion and his afternoon was over moments later following a high challenge by Popham which resulted in the number eight being sin-binned.
Popham made an immediate impact after his return when he charged over the Ulster line for Scarlets' opening try in the 32nd minute.
Steinmetz added an Ulster penalty before half-time but the Scarlets looked to have the advantage going into the second half.
Ulster threatened the Scarlets line in the 15 minutes after half-time but failed to make their possession count.
In contrast, the Scarlets' first decent move of the second half resulted in Regan King's try after replacement Justin Fitzpatrick had lost possession in his own 22.
Stephen Jones added the conversion and he was notching more extras in the 63rd minute when Stoddart crossed the Ulster line after yet more turnover ball.
As Ulster capitulated in injury-time, Peel and Gavin Thomas were able to stroll over unopposed for two more touchdowns as the Scarlets qualified for the last eight with their final group match against London Irish to spare.
Scarlets coach Phil Davies:
"I'm very pleased with the way we approached the game. We showed great character after some difficult results.
"We played with efficiency and intensity and it was great to get a five-try victory at Ravenhill.
"We learned a lot over Christmas but that has made us stronger. We knew we had a quality team that can play rugby."
Ulster coach Mark McCall:
"We were well beaten today. We had opportunities in both halves but we didn't take them.
"It was very disappointing to concede those late two tries which meant the final score was a bit misleading.
"But we lost the game in the first half when we were unable to establish a bigger lead."
Ulster: M Bartholomeusz, T Bowe, Andrew Trimble, P Steinmetz, P McKenzie, P Wallace, K Campbell, B Young, R Best, S Best (capt), J Harrison, M McCullough, N Best, K Dawson, R Wilson.
Replacements: Maggs for Steinmetz (58), Larkin for Wallace (36), J Fitzpatrick for B Young (55), P Shields for R Best (78), Barker for Harrison (58), Caldwell for McCullough (75).
Not Used: Marshall.
Scarlets: M Stoddart; D James, R King, G Evans, M Jones; S Jones, D Peel; I Thomas, M Rees, D Manu, A Jones, S MacLeod, S Easterby (capt), G Thomas, A Popham.
Replacements: M Watkins for M. Jones (36), C Stuart-Smith for Peel (80), J Davies for I Thomas (67), V Cooper for A Jones (75), D Jones for Popham (71).
Not Used: Owen, C. Thomas.
Sin Bin: Popham (23).
Referee: Joel Jutge (Fra)