The Scarlets marked their first visit to north Wales with a win and bonus point in front of 5,000 fans at Wrexham's
Racecourse Ground, one of the largest crowds seen in the competition.
Scarlets (25) 36
Tries: A Gravelle, T Selley, S Quinnell, R Rees. Cons: G Bowen (2). Pens: Bowen (4).
Borders (6) 20
Tries: G Graham, C Cusiter. Cons: G Morton (2). Pens: Morton (2).
The Llanelli team ran in four tries through Aled Gravelle, Tal Selley, Scott Quinnell and Richard Rees as they kept the
pressure on Ulster at the top of the Celtic League.
But after racing to a comfortable 25-6 half-time lead, the Scarlets were made to work by a determined Borders fightback in
the second period.
Tries soon after the break from prop George Graham and scrum-half Chris Cusiter left the Welsh fans sweating before they came
away with the deserved win.
The Scarlets' determination to play positive rugby as they courted the crowd shone through in a dominant first 40 minutes.
They fell behind to a third-minute penalty from Borders full-back Gareth Morton, but Scarlets hooker Gravelle soon
crossed for the first try following excellent work from Richard Rees.
Centre Selley, Llanelli's leading try scorer this season, added to
his tally by benefiting from a well-worked three-quarter move for the second five-pointer.
Selley continued his try-scoring form
Borders' misery continued when Morton was yellow-carded for a late tackle on
Llanelli fly-half Gareth Bowen, just before number eight Quinnell drove
through some weak defence from a five-yard scrum.
The Scarlets were disrupted by four key injuries in the forwards, though. Ian Boobyer (face), Vernon Cooper (hamstring), Quinnell (calf) and Gravelle (knee) all left the fray, disrupting the rhythm of the home side.
A Morton penalty gave Borders some encouragement before half-time, and after the break the
Wrexham crowd were stunned by the double strike from Graham and Cuister.
Morton converted both tries to make it 25-20 as the visitors pressed, but two penalties from Bowen and a try from wing Rees
sealed the game in the
Scarlets chief executive Stuart Gallacher was pleased with his side's venture to the north, despite heavy costs engendered in transporting the squad to Wrexham.
"We're investing in the future and it's money well spent," Gallacher told BBC Sport Wales. "It's been successful and we've had a good reaction from everyone up here.
"Players from the north are already starting to come through our academies. We'll be back here in March and we want to build on this."
Scarlets: Barry Davies; Richard Rees, Tal Selley, Matthew Watkins, Salesi Finau; Gareth Bowen, Dale Burn; Phil John, Aled Gravelle, John Davies, Vernon Cooper (capt), Adam Jones, Emyr Lewis, Ian Boobyer, Scott Quinnell.
Replacements: David Maddocks, Rhys Williams, Bryn Griffiths, Gareth Williams, Mike Phillips, Ceiron Thomas, Lee Byrne.
Borders: Gareth Morton; Cammie Murray, Jon Stuart, Kevin Utterson, Andy Turnbull; Clark Laidlaw, Chris Cusiter; George Graham, Ross Ford, Geoff Cross, Scott MacLeod, Colin Stewart, Campbell Feather, Dan Kane, Tony Walker.
Replacements: Stevie Scott, Craig Dunlea, Doddie Weir, Alastair Davidson, Iain Fairley, Scott Paterson, Calum MacRae.
Referee: David Keane (Ireland).