Llanelli 20 Leinster 18: Leinster's Felipe Contepomi hit the post with the last kick of the game as Llanelli clung on for a thrilling Celtic League victory at Stradey Park.
Ireland wing Denis Hickie crossed in the corner in the 86th minute of an enthralling encounter to give the Irish side a chance of salvaging a draw.
But Argentinian fly-half Contepomi's touchline kick hit the upright and the Scarlets celebrated a fourth consecutive league win and maintained their hopes of league glory his season.
Leinster included Brian O'Driscoll for only his third game since returning from the shoulder injury which ended his Lions tour in the summer, but the Ireland captain looked rusty in a match played at rapid pace.
It was O'Driscoll's Ireland midfield partner Gordon D'Arcy who opened the scoring after just five minutes with openside Keith Gleeson putting him free from halfway.
Contepomi converted and then carved open another chance, but O'Driscoll failed to hold a difficult pass.
The Scarlets then struck with two tries in the space of three minutes.
Centre Matthew Watkins claimed the first, intercepting a D'Arcy pass meant for O'Driscoll from 35 yards out.
But the second try was a superb combined effort from the home threequarters with full-back Barry Davies finishing off a slick move manufactured by Kiwi centre Regan King.
American fly-half Mike Hercus converted both and the Scarlets will feel they should have had another try in the opening 40 minutes, only to be twice denied on the line by stubborn Leinster defence.
A long-range kick from full-back Davies extended the home advantage to 17-7 just before half-time, but Contepomi responded for the visitors.
The Argentinian added three more points straight after the break, only for Hercus to hit back for the home side.
It was the Scarlets who were exerting most of the pressure, but again Leinster's defence was proving a tough one to pierce.
A subdued O'Driscoll left the field after 64 minutes to be replaced by fellow Lion Denis Hickie, himself coming back from the injury he picked up in New Zealand in the summer.
It was Leinster's turn to go on the attack in the closing stages with Hickie knocking on with the line beckoning.
But when his chance came again in injury time he made no mistake, only for Contepomi to fail with the extras, leaving Leinster with the consolation of a losing bonus point.
