The Scarlets kicked off Welsh rugby's Pro12 Judgement Day at the Millennium Stadium with victory in an entertaining and full-blooded encounter against Newport Gwent Dragons.
But the Scarlets were denied a bonus point try by the gutsy Dragons.
Scarlets George North and Jonathan Davies crossed while Owen Williams kicked 13 points.
Jonathan Evans and Daniel Evans scored Dragons tries, Tom Prydie adding two conversions and two penalties.
The win sent the Scarlets above Welsh rivals the Ospreys in the battle for a top-four play-off spot with the Ospreys having an immediate opportunity to take advantage in their 17:15 GMT kick-off at the same venue against Cardiff Blues.
The Scarlets topped a 79% possession share in the opening period as their edge at the scrum and in attack held sway.
But the scoreboard told a different tale when the opening period was over with the teams tied at 10-10.
With the Dragons having suffered a 52-19 drubbing by the Ospreys in the previous round, there was perhaps an air of over-confidence about the Scarlets in the opening stages.
Evidence of that came when they responded to an early penalty award by kicking for the corner and an attacking, close-range line-out instead of attempting a shot at goal.
The Scarlets' self belief seemed understandable when their off-loading approach brought North's try.
Fly-half Williams launched a counter-attack and found half-back partner Aled Davies, whose deft pass sent Northampton target North powering through the Dragons defence.
Williams had already opened the scoring with a 20th minute penalty and he added the conversion to the wing's try.
And the absence of North's Wales team-mate Toby Faletau, who was in the sin-bin for collapsing a maul, ensured there was a gap in the Dragons' defensive formation.
However, the Scarlets had not made enough of their dominance of territory and possession.
And after Dragons scrum-half Jonathan Evans illegally impeded opposite number Davies at a scrum, Scarlets fly-half Williams' penalty attempt rebounded off an upright.
The Dragons then took advantage of some loose play and poor option taking by the Scarlets to strike back.
Scrum-half Evans was alive to the opportunity, dummying past prop Phil John on the Scarlets 22 and racing over for Prydie to convert.
Prydie, the youngest Test cap in Welsh history, then levelled the scores after Scott Williams' illegal work at a ruck to leave the Scarlets wondering how they were not well ahead at the break.
Owen Williams and Prydie exchanged penalties after the break to maintain the deadlock before the Scarlets' fly-half edged them back in front.
The Scarlets pivot hit an upright for the second time in the 65th minute to leave the outcome finely balanced.
But tries in quick succession by Jonathan Davies and North put paid to the Dragons' spirited effort.
Centre Davies profited from midfield partner Scott Williams' approach work to score on his 100th Scarlets appearance with Owen Williams converting.
And from the restart Davies launched the attack that ended with North's second try following Gareth Owen and Ken Owens' impressive link work.
The Dragons were not done, however, as impressive former Scarlet Daniel Evans - having been switched from full-back to fly-half - used his power to ride Owens' tackle and score.
Daniel Evans then earned Scrum V pundit and Wales dual code legend Jonathan Davies' vote as Man-of-the-Match.
But he and his team-mates were left to ponder defeat and the Scarlets their missed opportunities in the hunt for a bonus point.
Dragons: Tom Prydie; Will Harries, Pat Leach, Jack Dixon, Ross Wardle; Dan Evans, Jonathan Evans; Aaron Coundley, Hugh Gustafson, Dan Way, Andrew Coombs (capt), Rob Sidoli, Dan Lydiate, Toby Faletau, Nic Cudd.
Replacements: Adam Hughes for Wardle (64), Owen Evans for Coundley (69), Sam Parry for Gustafson (56), Nathan Buck for Way (59), Jevon Groves for Sidoli (62), Ieuan Jones for Lydiate (62), Steffan Jones for Hughes (80).
Not Used: Wayne Evans.
Scarlets: Gareth Owen; George North, Jonathan Davies, Scott Williams, Liam Williams; Owen Williams, Aled Davies; Phil John, Matthew Rees, Samson Lee, George Earle, Johan Synman, Aaron Shingler, Rob McCusker (capt), Johnathan Edwards.
Replacements: Gareth Maule for Owen (75), Aled Thomas for O Williams (72), Rhodri Williams for Aled Davies (70), Rhodri Jones for John (70), Ken Owens for Rees (41), Deacon Manu for Lee (58), Sione Timani for Earle (69), Josh Turnbull for Edwards (53).
Referee: Neil Paterson (SRU)
Assistant Referees: Neil Hennessy, Jon Mason (both WRU)
Citing Commissioner: Ray Wilton (WRU)
TMO: Tony Rowlands (WRU)