Dragons (3) 15
Scarlets (10) 13
Tries: Pen
Con: Priestland
Pens: Priestland (2)
A last-minute try from Richard Mustoe saw the Dragons complete the double over the Scarlets and denied the visitors top spot in the league.
A penalty try and Rhys Priestland's boot gave the Scarlets a 10-0 lead in a scrappy, whistle-dominated derby.
The Dragons levelled with a Ceri Sweeney penalty and Ashley Smith's well-taken second-half try.
Priestland edged the visitors back ahead with a kick, before Mustoe struck with the final move of the game.
606: DEBATE
The opening quarter continued the dour, low quality standard that has been seen in the Welsh derbies over the Christmas period, with Priestland's sixth-minute penalty the only score.
A sharp Morgan Stoddart break lifted the gloom over Rodney Parade and set up the attacking position from which the visiting forwards took advantage.
The Scarlets eight drove powerfully from a scrum in the shadow of the posts, and, when the Dragons front row stood up, referee James Jones did not hesitate in awarding a controversial penalty try.
The home side got on the scoreboard with a Sweeney penalty after James Bater had been sin-binned for killing the ball at a ruck in front of the Scarlets' posts.
"We've been waiting for a result like that for ages"
The Llanelli side held out with 14 men, but the Dragons - with man-of-the-match Joe Bearman to the fore - got on a roll after the break with a powerful scrum in the visitors' 22.
The ball came out to the three-quarters, where Sweeney made space and freed Smith on his shoulder, the young centre crossing for a converted try that levelled the scores.
Priestland, starting because of Stephen Jones' thumb injury, restored the lead with a penalty after Dragons indiscipline.
The home side rallied in a lively final quarter, but seemed to lack the inspiration to break down the visitors.
A kickable penalty three minutes from time was booted to touch by Sweeney, but the Dragons lost the resultant line-out on the visitors' line.
The chance of victory seemed to have gone, but Richard Fussell and Kevin Morgan combined well in midfield in a desperate final attack, freeing Mustoe who slid in at the corner.
The victory was just the second for the Dragons in their last 10 games and marks the first time they have completed the double over the Scarlets.
The Llanelli side have not won on the road since 5 October.
"I'm really happy for the boys, it's about time we got that sort of a win."
Dragons: Morgan, Fussell, Emerick, Smith, Mustoe, Sweeney, A. Williams, Gustafson, S. Jones, R. Thomas, A. Jones, Sidoli, Bearman, Charvis, Owen.
Replacements: Walker for A. Williams (79), Black for Gustafson (47), Daly for S. Jones (58), Harris for Sidoli (68). Not Used: Hall, Dolman, A. Thomas.
Scarlets: Stoddart, James, King, J. Davies, M. Jones, Priestlend, Peel, I. Thomas, Hayter, Douglas, Cooper, MacLeod, Easterby, Bater, N. Thomas.
Replacements: Brew for J. Davies (47), Manu for I. Thomas (45), Eustace for Cooper (80), D. Jones for N. Thomas (76). Not Used: George, L. Davies, C. Thomas.
Att: 6,702
Referee: James Jones (WRU)
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