Leinster 31 Llanelli 20
Leinster made it four wins in a row in their final home league fixture of 2003, as tries from Australian centre Christian Warner and wing John McWeeney saw them hand Llanelli their first loss on their travels.
Two McWeeney tries in three second-half minutes killed off the Scarlets' challenge, with scrum-half Brian O'Meara's contributing 16 points with the boot.
It was a lively opening from both sides with Leinster, backed by a slight breeze, pinning the visitors back into their 22 after three minutes, and a high tackle from wing Salesi Finau gave O'Meara his first penalty success from in front of the posts.
Gareth Bowen replied barely 60 seconds later from inside the Leinster 10 metre line, for what proved to be the Scarlets' only score of the first half.
The visitors almost had the game's first try on 11 minutes but flanker Ian Boobyer knocked on when attempting to burrow over from close range.
Gary Ella's side got the crucial score in the 27th minute when a run from full-back Gordon D'Arcy from his own 22 saw him exchange passes with Gary Brown and prop Niall Treston before Warner arrived onto a flat pass from David Quinlan to outpace Barry Davies to the Welsh line.
O'Meara converted and a third success with the boot gave the home side a 13-3 lead after half an hour.
A third penalty from O'Meara went straight over in the fourth minute of injury time, before Llanelli's Bowen brought the visitors back to within 10 points after four minutes of the second half with a penalty.
A moment of controversy followed with the sin-binning of Leinster lock Ben Gissing and Scarlets' prop John Davies for infringing, only for Davies to rejoin the action a minute later.
Referee Rob Dickson failed to notice but yellow-carded lock James Griffiths three minutes later, and with play continuing, McWeeney scored his brace on 54 and 56 minutes.
The Welsh side scored a consolation try through centre Tal Selley, his fourth of the season coming from close range in the 72nd minute.
Llanelli attempted to pummel the home line in the closing stages, with a bout of sustained pressure seeing Boobyer cross in the stoppage time, full-back Barry Davies converting