The Scarlets scraped past the Dragons 10-6 in a hard-fought Pro12 clash at Rodney Parade on Friday.
In a dull game, the Scarlets scored first through Jonathan Edwards, but two Jason Tovey penalties saw the Dragons remain in contention at the break.
Both sides struggled to break through opposing defences, although the Dragons' Lewis Robling missed three second half three-point opportunities. A late Dan Newton penalty sealed the visitors' win.
Despite being in play-off contention, the Scarlets made 14 changes for their visit to their Welsh rivals.
However, it was the hosts who initially struggled to impose themselves, particularly as the visitors opened up a 7-0 lead after 18 minutes.
After good hands from props Phil John and Deacon Manu, Newton eventually received the ball before the full-back drew the last defender and sent Edwards over.
But the Dragons ground themselves back into the match and reduced the gap to one point at half-time.
On 25 minutes, Tovey scored his first penalty and then added another after Scarlets' forward Kieran Murphy was sin-binned.
Another scrappy period followed in the second half and the first opportunity for points occurred for the visitors through Newton, but he missed the target.
With their main kicker, Tovey, off the field through injury Newport's Robling missed three chances himself.
It was backs to the wall for an inexperienced Scarlets' side missing their big stars, but Newton managed to slot the crucial penalty and garner them a vital win.
Pens: Tovey 2
Try: J. Edwards
Pen: A Thomas
Dragons: 15 Martyn Thomas, 14 Tonderai Chavhanga, 13 Adam Hughes, 12 Lewis Robling, 11 Aled Brew, 10 Jason Tovey, 9 Wayne Evans, 8 Toby Faletau. 7 Gavin Thomas, 6 Danny Lydiate, 5 Rob Sidoli, 4 Adam Jones, 3 Nathan Buck, 2 Lloyd Burns, 1 Nathan Williams.
Replacements: 16 Steve Jones, 17 Phil Price, 18 Dan Way, 19 Jevon Groves, 20 Lewis Evans, 21 Joe Bedford, 22 Anitelea Tuilagi, 23 Will Harries.
Scarlets: 15 Dan Newton, 14 Viliame Iongi, 13 Adam Warren, 12 Gareth Maule (capt), 11 Andy Fenby, 10 Aled Thomas , 9 Rhodri Williams, 8 Kieran Murphy, 7 Johnathan Edwards, 6 Josh Turnbull, 5 Dominic Day, 4 Sione Timani, 3 Deacon Manu, 2 Ken Owens, 1 Phil John.
Replacements: 16 Emyr Phillips, 17 Iestyn Thomas, 18 Peter Edwards, 19 Lou Reed, 20 Richie Pugh, 21 Gareth Davies, 22 George North, 23 Daniel Evans.
Venue: Rodney Parade
Referee: Neil Hennessy (Wales)
Assistant referees: Gwyn Morris (Wales), Huw David (Wales)
Television match official: Tony Rowlands (Wales)