Scarlets broke their losing sequence of five defeats with an uninspiring Pro14 victory over Dragons.
Dan Jones kicked 12 points in a poor first-half while wing Ioan Nicholas and replacement Sam Hidalgo-Clyne scored second-half tries.
Dragons could only manage a late consolation score through replacement flanker James Benjamin.
Scarlets were led to victory by Wales hooker Ken Owens who impressed playing out of position at number eight.
Wayne Pivac’s side bounced back from last weekend’s 34-5 home defeat by Cardiff Blues, an eighth loss in 10 matches, as they avoided a clean sweep of festive derby defeats.
It kept Scarlets in the hunt of finishing in the top three of Conference B and reaching the Pro14 play-offs.
Dragons could not build on their 23-22 home victory over Ospreys at Rodney Parade which was their first league win over a Welsh region in four years.
The Gwent region have now lost their last 39 away league games with the last victory coming at Treviso in March 2015.
Caretaker coach Ceri Jones has been in charge for four games since Bernard Jackman’s departure and could be in charge for the Challenge Cup match against Timisoara Saracens next Friday.
Dragons were exposed in the front-row as they missed four props before the game with Ryan Bevington, Brok Harris and Leon Brown injured and Lloyd Fairbrother suspended.
Aaron Jarvis limped off in the 16th minute to compound issues and there was no surprise when Dan Suter was yellow-carded in the first-half for continually collapsing.
Scarlets had their own injury concerns, especially in the back-row with Owens packing down at eight because of injures to James Davies, Aaron Shingler, Will Boyde, Blade Thomson, Josh Macleod and Uzair Cassiem.
Scarlets recalled Dan Jones at 10 as Wales centre Hadleigh Parkes moved back to his preferred position after two starts at fly-half. Jones responded with a man-of-the-match display after Pivac had criticised his form before the game.
Tyler Morgan and Jack Dixon were back in the Dragons’ midfield among five changes but back-rower Ross Moriarty’s concussion kept him out.
Scarlets forced two early scrum penalties which Jones slotted over, and with Wales scrum-half Gareth Davies not included in the match-day squad, teenager Kieran Hardy showed some class with a 70-yard break.
This was the only spark of a poor opening quarter dogged by scrum penalties as referee Craig Evans struggled to control affairs.
Former Scarlet Josh Lewis hit the post with an early attempt before slotting the Dragons’ opening points.
Scarlets adapted more direct running tactics in the final minutes of the first-half with Rob Evans denied a try after South African full-back Zane Kirchner was adjudged to have held up the Wales prop.
Jones kicked two penalties, one from which Suter was sin-binned, to hold a nine-point lead after dominating possession and territory.
While the visitors were down to 14 men, Lewis slotted over a second penalty.
Scarlets finally remembered the successful attacking system they have employed in the last couple of seasons with some smart passes from a backline movement allowing Nicholas to dive over in the right-hand corner.
The home side’s pressure continued and yielded a second try for Hidalgo-Clyne who burrowed over from a quickly taken penalty.
Dragons completed the scoring when Hallam Amos offloaded out the back door to Adam Warren who passed back inside for Benjamin’s try, which Jason Tovey converted.
It was a welcome victory for Scarlets with cheers at the end rather than boos that followed the Blues defeat.
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Scarlets head coach Wayne Pivac said: “We were desperate for a win so we were pleased with that and it keeps us alive.
“The ball in play time was very low and it was apparent there was a lot going on at the scrum.
“I felt all the penalties should have gone our way in that areas because we were dominant.”
Dragons backs coach Barry Maddocks: “With the front-row injuries we had at the start of the week we did not have the platform we needed and they had a strong scrum.
“When we had the ball the boys played some good stuff. It was always going to be tough with territory and possession down to around 30 per cent.
“The energy and effort was outstanding and it has been a good month for the Dragons.”
Scarlets: Johnny McNicholl; Ioan Nicholas, Jonathan Davies, Hadleigh Parkes, Paul Asquith; Dan Jones, Kieran Hardy; Rob Evans, Ryan Elias, Samson Lee, Josh Helps, David Bulbring, Ed Kennedy, Ken Owens (capt), Dan Davis
Replacements: Marc Jones, Wyn Jones, Werner Kruger, Tom Price, Tom Phillips, Sam Hidalgo-Clyne, Steff Hughes, Tom Prydie.
Dragons: Zane Kirchner; Adam Warren, Tyler Morgan, Jack Dixon, Hallam Amos; Josh Lewis, Tavis Knoyle; Aaron Jarvis, Richard Hibbard, Dan Suter, Brandon Nansen, Matthew Screech, Cory Hill (capt), Aaron Wainwright, Harrison Keddie.
Replacements: Elliot Dee, Gerard Ellis, Chris Coleman, Joe Davies, James Benjamin, Rhodri Williams, Jason Tovey, Jordan Williams.