The Scarlets are in danger of missing out on next year's Heineken Cup after going down 23-17 to Munster in the Magners League on Thursday.
Jean de Villiers and James Coughlan scored a try apiece as the hosts moved 17-8 ahead for half-time, and outside-half Paul Warwick maintained his 100 per cent kicking return with two second-half penalties.
They were made to fight all the way for the points, though, as the spirited Scarlets, with number 10 Rhys Priestland scoring a try and four penalties, fought back to claim a losing bonus point and they threatened even more.
A late surge from winger Andy Fenby saw Munster forced to scramble back towards their 22 and the Scarlets deserved more as the attack petered out without what they felt was a certain penalty.
The Welshmen got off to a whirlwind start when Priestland charged down a kick from his opposite number Warwick and showed a very good turn of pace to make it over in the right corner.
Munster recovered well and made yards through their forwards, with team captain Mick O'Driscoll to the fore in a lineout drive, before South African centre De Villiers edged past Jonathan Davies to score from close range.
Warwick's successful conversion put Munster 7-5 up, but with number eight Coughlan failing to gather the restart, the Scarlets were straight back on the attack with Richie Pugh stopped just metres out.
Nigel Davies' men held the edge in terms of possession and territory in an error-strewn first half, with some strong carries from inspirational skipper David Lyons and individual play from Davies and Josh Turnbull.
Priestland slotted his second penalty, six minutes before the break, to nose the visitors back in front - however, their lead was a short-lived one.
Their tighthead prop Deacon Manu was sin-binned for pulling Nick Williams back as Munster threatened near the Scarlets' 22. Tony McGahan's side used the extra man to string together their best attacking phase and Billy Holland and Doug Howlett kept them on the front foot, before Coughlan plunged over for a seven-pointer.
The second half ebbed and flowed as the place-kickers traded blows - two Priestland successes, sandwiching a Warwick kick, reduced the arrears for the Scarlets to 20-14.
With defences on top, the place-kicks were becoming increasingly vital and Warwick, from a tough angle on the right, landed what proved to be the match-winning kick in the 65th minute.
Munster went through the phases as they went in search of a try to seal it, but their accuracy was not at the required level, despite the best efforts of O'Driscoll, Ian Dowling and Niall Ronan.
The Scarlets mustered a final rally, helped by Tommy O'Donnell's sin-binning for slowing up ruck ball. Priestland completed his 17-point tally but there was no further reward for Lyons and company as Munster got back to winning ways.
Tries: De Villiers, Coughlan
Cons: Warwick 2
Pens: Warwick 3
For the Scarlets:
Pens: Priestland 4
Munster: 15 Scott Deasy, 14 Doug Howlett, 13 Tom Gleeson, 12 Jean de Villiers, 11 Ian Dowling, 10 Paul Warwick, 9 Peter Stringer, 8 James Coughlan, 7 Niall Ronan, 6 Nick Williams, 5 Billy Holland, 4 Mick O'Driscoll (capt), 3 Julien Brugnaut, 2 Damien Varley, 1 Marcus Horan.
Replacements: 16 Denis Fogarty, 17 Donncha Ryan, 18 Alan Quinlan, 19 Tommy O'Donnell, 20 Duncan Williams, 21 Jeremy Manning, 22 Denis Hurley.
Scarlets: 15 Dan Newton, 14 Joe Ajuwa, 13 Regan King, 12 Jonathan Davies 11 Andy Fenby, 10 Rhys Priestland, 9 Tavis Knoyle, 8 David Lyons (capt), 7 Richie Pugh, 6 Josh Turnbull, 5 Dominic Day, 4 Lou Reed, 3 Deacon Manu, 2 Ken Owens, 1 Iestyn Thomas.
Replacements: 16 Phil John, 17 Emyr Phillips, 18 Damian Welch 19 Rob McCusker, 20 Martin Roberts, 21 Daniel Evans, 22 Gareth Maule.
Referee: Neil Paterson (SRU)
Assistant Referees: D Phillips (IRFU) D Connolly (IRFU)
TMO: Sean Flannery (IRFU)