Leinster lost at home in the Magners League for the first time in almost two years as Llanelli Scarlets ran out emphatic winners at the RDS Showgrounds.

The Leinster defence fell asleep for a crucial period coming up to the hour mark and the Scarlets seized their chance, running in four tries in the space of 11 minutes to canter clear.

The game had been tight up to then, with Phil Davies' men taking a 16-11 advantage into the interval.

But quickfire tries from captain James Bater, back row colleague Jonathan Edwards (two) and Kiwi centre Regan King left Leinster's bid to equal Cardiff's league record of 16 successive home wins in tatters.

It was an electric start from both sides, with Morgan Stoddart and King combining on the left wing to put winger Matthew Watkins charging for a third-minute try - his 28th in league history, drawing him level with record holder Denis Hickie of Leinster.

Rhys Priestland converted but there was an instant reply from the hosts as Shane Jennings barged through on the restart and centre Christian Warner crossed in the left corner.

Jonathan Sexton knocked his conversion attempt off the post and the remainder of a half, scoring wise, was fought out between the young fly-halves.

The 20-year-old Priestland landed three successful penalty kicks and Sexton, 22, fired over twice after two initial misses.

The Scarlets were full value for their five-point half-time lead and despite losing lock Vernon Cooper to 37th-minute yellow card, they defended their try-line resolutely.

A Gavin Evans break, five minutes after the restart, almost saw them in for their second try.

A nightmare few minutes followed for Leinster full-back Rob Kearney as both he and prop Juan Francisco Gomez hesitated far too long in tackling the advancing Bater and the Scarlets skipper was allowed to cruise over for a 51st-minute try.

Moments later, Kearney went offside at a ruck under the Leinster posts, deliberately slowing up Llanelli ball, and got a yellow card for his troubles.

The floodgates began to open as Priestland kicked the resulting penalty and man of the match Edwards then rumbled over for an unconverted try to put the Welshmen 31-11 in front.

Worse followed for Leinster when foul language directed at referee James Jones landed flanker Jennings in the sin bin.

Making use of their two-man advantage, the Scarlets put King and Edwards over for further tries as the bonus point was gleefully garnered.

Leinster's first home league defeat since November 2005 was all but confirmed and though a yellow card for Bater helped the hosts carve out consolation tries for Stan Wright and Jamie Heaslip, the Scarlets had the last word when full-back
Stoddart sliced through for his side's sixth try in the 10th minute of injury-time.

Leinster 23 (11)
Tries: Warner, Wright, Heaslip.
Cons: Sexton.
Pens: Sexton 2.

Scarlets 52 (16)
Tries: Watkins, Bater, Edwards 2, King, Stoddart.
Cons: Priestland 5.
Pens: Priestland 4.

Leinster: Rob Kearney; Gary Brown, Fergus McFadden, Christian Warner, Luke Fitzgerald; Jonathan Sexton, Cillian Willis; Juan Francisco Gomez, Bernard Jackman, Stephen Knoop; Trevor Hogan, Leo Cullen (capt), Shane Jennings, Keith Gleeson, Jamie Heaslip.

Replacements: Brian Blaney for Jackman (64), Stan Wright for Knoop (41), Devin Toner for McFadden (75), Cameron Jowitt for Hogan (50), Stephen Keogh for Gleeson (55), Chris Keane for Willis (66), Ross McCarron for Brown (28).

Scarlets: Morgan Stoddart; Garan Evans, Regan King, Gavin Evans, Matthew Watkins; Rhys Priestland, Liam Davies; Phil John, James Hayter, Deacon Manu, Vernon Cooper, Adam Eustace, James Bater (capt), Jon Edwards, Dafydd Jones.

Replacements: Ben Broster for John (68), Ken Owens for Hayter (41), Lou Reed for Eustace (74), Gavin Thomas, Gavin Cattle for L. Davies (47), Jon Davies for Watkins (80), Nathan Brew for Garan Evans (47).

Referee: James Jones (WRU).