Leinster 39 Scarlets 7:Michael Cheika's side kept pace with chief rivals London Irish at the top of Pool Six as they warmed up a chilly RDS with a seven-try dismissal of the Scarlets.

The reigning Heineken Cup champions made it a blue Christmas for the depleted Scarlets as Rob Kearney, Gordon D’Arcy and Brian O’Driscoll grabbed two tries each.

Shane Horgan also crossed the Scarlets’ whitewash, while the visitors’ only response came in the final quarter when full back Rhys Priestland broke through for a converted score.

The result keeps Leinster on course for a huge Pool Six decider with London Irish at the Madjeski Stadium next month, with both sides currently locked together on 15 points after the Exiles picked up a late bonus point in their 34-13 win at home to Brive .

As in last weekend’s 32-7 victory at Parc y Scarlets, three first-half tries set the tone for Cheika’s men against a Scarlets side that struggled to maintain any sort of attacking momentum.

The key moment came just before half-time when, just as the Scarlets looked set to cross the Leinster try-line, Deacon Manu’s pass was intercepted by Horgan, who outstripped Stephen Jones and Priestland to finish from 80 metres out.

The Scarlets, who had Priestland at full back and Darren Daniel and Johnathan Edwards back in the side, made a confident start and Leinster outhalf Shaun Berne was skittled to the ground by his countryman David Lyons, the Scarlets skipper.

However, Leinster comprehensively dominated the physical exchanges and their meaty scrum, led by South African CJ van der Linde before his injury-forced withdrawal, had the visitors under all sorts of pressure.

It was not all plain sailing, though, as full back Kearney dropped his first two high balls and Berne struggled with his place-kicks into an icy wind.

But the Scarlets defence gave way after eight minutes when Kearney managed to slide in at the left corner, taking a pass from Horgan after Van der Linde and Berne had made headway into the 22.

Berne missed the conversion and his opposite number, Stephen Jones, also struggled with the boot — missing two penalty attempts in quick succession that the Wales and Lions star would usually convert.

The Scarlets lost the services of a bloodied Andrew Fenby and they leaked a second try when Horgan gathered Berne’s crossfield kick and the big winger fed Kearney, who made the line despite the best efforts of replacement Gareth Maule.

Sean Lamont, Lyons and Simon Easterby, who competed tigerishly in his 200th appearance for the club, helped the Welsh region rally before half-time.

They got within sight of the Leinster whitewash only for Manu’s pass, with a two-man overlap, to be snaffled by Horgan in devastating fashion. Berne again failed to add the extras, leaving it 15-0 at the break.

The Scarlets’ resolve had been broken and Leinster cruised through the second half, securing the bonus point within six minutes as D’Arcy danced through from close range.

An Isa Nacewa break did the initial damage, the home forwards battered away, with man-of-the match Jamie Heaslip just metres away from marking his 100th Leinster appearance with a try.

Possession was turned over in front of the Scarlets posts but D’Arcy was alert to it and kept the move going, stepping off his right to deliver a knockout blow to the Welshmen.

Berne broke his duck with the successful conversion and Daniel and Priestland were soon powerless as O’Driscoll muscled his way over for the fifth try, with support from Kearney and replacement Bernard Jackman.

A superb catch by Kearney, a decibel-raising run from Jackman and a sweet draw and feed from Berne preceded D’Arcy’s second try, which Berne converted from the right.

Starved of territory, the Scarlets lifted the siege just past the hour mark and, with Kearney foiled by the bounce of the ball, Priestland hared through for a consolation try.

But, showing no mercy, Leinster had the final say when replacement Fergus McFadden fed O’Driscoll for a simple score in the left corner.