A below-strength Munster suffered another defeat in their final match before the Heineken Cup final in a dire Celtic League contest at Stradey Park.
With Munster coach Declan Kidney opting to rest the majority of his key men ahead of the Millennium Stadium clash with Biarritz a week on Saturday, the Scarlets were able to grind out a vital win for their own European ambitions.
It was not pretty though with the home side having to rely on a powerful forward platform to gain them four crucial points in their bid to finish among the top three Welsh regions.
With both sides missing numerous international players, the match had a typical end-of-season feel about it in.
Errors and the whistle of Scottish referee Malcolm Changleng dominated for long periods in the first half with neither side able to gain any significant momentum.
It was Munster who were first on the scoreboard after 15 minutes thanks to a 35-yard penalty from outhalf Jeremy Manning after the Scarlets were caught offside at a ruck.
But with the home forwards gaining a stranglehold, the Scarlets managed to respond just three minutes before the half-time whistle.
The Munster scrum was under pressure all evening and five yards out they eventually buckled with outstanding Wales number eight Alix Popham touching down.
However, outhalf Craig Evans, on his Celtic League debut, missed with the simple conversion.
Manning made no mistake 12 minutes after the resumption and Munster were back in front, although it did not last long with Evans successful from the touchline moments later.
But there was little to cheer a crowd of 5,754, which took the Celtic League's attendances past the half million mark for the season for the first time in the league's history.
That was until Popham claimed his second thanks to a barnstorming break from replacement hooker Aled Gravelle on 64 minutes.
With little appearing on Gravelle dummied and raced clear from a maul and although he was tackled short of the line the number eight was able to power over from close range.
Evans converted and then landed a long-range penalty from inside his own half to extend the lead to 18-6.
And although Scarlets lock Vernon Cooper was sin-binned late on, the home side were able to hold out without any scares.
