Scarlets outscored Gloucester two tries to one to claim a hard-fought 13-7 win over Gloucester in Friday's Anglo-Welsh Cup clash at Parc y Scarlets.
The win keeps the Welsh region's hopes of progressing to the knock-out stages alive while it leaves Gloucester with only one win from three games.
Scarlets led 5-0 at the break thanks to a try from centre Steffan Hughes, who went over in at the left corner.
Gloucester centre Billy Burns burst through an attempted double tackle to score the equalising try after 55 minutes before adding the conversion that gave the Cherry and Whites the lead.
But the English team's advantage only lasted five minutes as Josh Lewis kicked a penaltyto put the host back in front by a single point.
Gloucester had a golden opportunity to regain the lead but Burns was short of the mark with a 40-metre penalty shot.
It was a key moment and three minutes from time the Scarlets sealed the win with a try for wing Aaron Warren who ran in from 25 metres out.
Tries: Hughes, Warren
Scarlets: 15 Jordan Williams, 14 Kristian Phillips, 13 Steffan Hughes, 12 Adam Warren, 11 Aaron Warren, 10 Josh Lewis, 9 Aled Davies, 8 Sione Timani, 7 Craig Price, 6 Josh Turnbull (c), 5 Johan Snyman, 4 Richard Kelly, 3 Jacobie Adriaanse, 2 Kirby Myhill, 1 Rob Evans.
Replacements: 16 Darran Harris, 17 Wyn Jones, 18 Horatiu Pungea, 19 Carwyn Jones, 20 Lewis Rawlins, 21 Connor Lloyd, 22 Gareth Owen, 23 Kyle Evans
Gloucester: 15 Martyn Thomas, 14 Steph Reynolds, 13 Andrew Bulumakau, 12 Billy Burns, 11 Drew Cheshire, 10 Jonny Bentley, 9 Tavis Knoyle, 8 Lewis Ludlow, 7 Alex Woodburn, 6 Ross Moriarty, 5 Tom Hicks, 4 Will James (c), 3 Rupert Harden, 2 Koree Britton, 1 James Gibbons
Replacements: 16 Dan George, 17 Dan Murphy, 18 Tom Heard, 19 Jonny Hill, 20 Sione Kalamafoni, 21 Reece Boughton, 22 Lloyd Evans, 23 Will Hayward
Venue: Parc y Scarlets
Kickoff: 19:30 GMT
Referee: Neil Hennessy (Wales)
Assistant Referees: Chris Williams (Wales), Jason Langdon (Wales)