Tries from Ryan Jones and Hanno Dirksen helped the Ospreys claim a 23-16 victory over the Scarlets in the PRO12 at Parc y Scarlets on Friday.
In a tense and scrappy opening period - largely dominated by kicking - Dan Biggar slotted three penalties to Rhys Priestland's two efforts.
And after Priestland had levelled with his third three-pointer, Jones and Dirksen touched down late on to give the visitors their first win of the campaign, despite a late try from George North.
The two sides have endured contrasting fortunes so far this season. While the Llanelli-based outfit have emerged victorious in their first three encounters, the Ospreys have recorded the opposite - defeat in every PRO12 game thus far.
It was the hosts who started the brighter and looked to take advantage of a potential lack of confidence in the visitors' ranks. And they opened the scoring with a Priestland penalty from a breakdown infringement after four minutes, but Biggar responded with one of his own to level.
The Scarlets' fly-half added a second three-pointer as the home side regained their advantage before the away side's fly-half once again got the Ospreys back into the game.
Biggar then scored his third from the tee to put his side into a 9-6 half-time lead.
There wasn't much change in the second-half either with the match remaining attritional.
Priestland's early penalty was all either team had to show for most of the period. However, the Ospreys hadn't read the script and went over for two late touchdowns to seal the win.
North did score late on for the hosts to rescue a bonus-point but it wasn't enough.
Pen: Priestland 3
Tries: Jones, Dirksen
Con: Biggar 2
Pen: Biggar 3
Scarlets: 15 Liam Williams, 14 George North, 13 Jonathan Davies, 12 Scott Williams, 11 Andy Fenby, 10 Rhys Priestland, 9 Tavis Knoyle, 8 Rob McCusker (capt), 7 Josh Turnbull, 6 Aaron Shingler, 5 Richard Kelly, 4 George Earle, 3 Deacon Manu, 2 Ken Owens, 1 Phil John.
Replacements: 16 Matthew Rees, 17 Peter Edwards, 18 Samson Lee, 19 Sione Timani, 20 Johnathan Edwards, 21 Gareth Davies, 22 Aled Thomas, 23 Gareth Maule.
Ospreys: 15 Richard Fussell, 14 Hanno Dirksen, 13 Tom Isaacs, 12 Andrew Bishop, 11 Tom Grabham, 10 Dan Biggar, 9 Kahn Fotuali'i, 8 Joe Bearman, 7 Justin Tipuric, 6 George Stowers, 5 Ian Evans, 4 Alun Wyn Jones (capt), 3 Aaron Jarvis, 2 Richard Hibbard, 1 Duncan Jones.
Replacements: 16 Scott Baldwin, 17 Ryan Bevington, 18 Joe Rees, 19 Jonathan Thomas, 20 Ryan Jones, 21 Rhys Webb, 22 Matthew Morgan, 23 Jonathan Spratt.
Referee: Leighton Hodges (Wales)
Assistant referees: Gwyn Morris (Wales), Jon Mason (Wales)
Television match official: Derek Bevan (Wales)