Newport Gwent Dragons ended a 10-match losing run against the Scarlets in a compelling Welsh Pro12 derby at Rodney Parade.
Phil Price and ex-Scarlet Dan Evans both went over for the hosts as they built a 17-3 lead.
Rhys Priestland's kicking and a Scott Williams try boosted Scarlets' hopes.
But the Dragons held out in a second half in which Jason Tovey and Tom Prydie edged the kicking duel with in-form Priestland.
Victory for the hosts also came in the wake of six defeats by Welsh regional rivals in 2012-13 to underline their early-season improvement.
The first Welsh derby of the season got under way with the visitors soon on the back foot, largely due to the adventurous approach of the Dragons - and much joy came through wing Prydie.
Prop Price took Argentine front-row team-mate Francisco Chaparro's offload for the first try, which Tovey converted.
Priestland kicked the first points for the visitors before the Dragons again established themselves deep in Scarlets territory.
The away side were guilty of running into rather than out of trouble near their own posts where flanker Lewis Evans' textbook breakdown steal set up the next score.
Patience was crucial in the build-up and scrum-half Richie Rees delayed the final pass perfectly, allowing full-back Evans to go over.
Tovey converted to give the Dragons a 17-3 lead, but that was soon cut to 11 points by Priestland's second successful kick.
Rob McCusker's athletic effort in cover defence brought down Dragons wing Hallam Amos at the corner - and that intervention looked even more important when Jonathan Davies gave centre partner Scott Williams the chance to sidestep through the remaining defence.
Priestland converted and having been under pressure for much of the opening period, the Scarlets trailed by only four points at the break.
Priestland and Tovey exchanged penalties to keep the contest finely balanced going into the final quarter - but Prydie's 69th-minute penalty from the left-hand touchline gave some breathing space.
The visitors had the Dragons under pressure with a series of late scrums, but they could not control the final drive, giving Toby Faletau the chance to gather and prompt the final whistle with his clearance.
Dragons: Dan Evans, Tom Prydie, Ross Wardle, Jack Dixon, Hallam Amos, Jason Tovey, Richie Rees; Phil Price, Rhys Thomas, Francisco Chaparro, Andrew Coombs (capt), Matthew Screech, Jevon Groves, Lewis Evans, Toby Faletau.
Replacements: Hugh Gustafson for R Thomas (8), Burton for Tovey (78), O Evans for Price (56), Sidoli for Screech (68), Talei for Groves (63), J Evans for Rees (60), Dan Way Chaparro (55), Hughes for Wardle (72).
Scarlets: Gareth Owen; Liam Williams, Jon Davies, Scott Williams, Jordan Williams; Rhys Priestland, Gareth Davies; Phil John, Ken Owens, Samson Lee, Jake Ball, George Earle, Aaron Shingler, Rob McCusker (capt), John Barclay.
Replacements: Reynolds for Owen (21), A Davies for G Davies (71), E Phillips for Owens (63), R Evans for John (63), Adriaanse for Lee (63), Kelly for Earle (70), Turnbull for A Shingler (60). Not used: A. Thomas.
Referee: Nigel Owens (WRU)
Assistant referees: Ian Davies, Jon Mason (both WRU)
Citing commissioner: Gwyn Bowden (WRU)
TMO: Gareth Simmonds (WRU)