Leinster moved top of the BKT United Rugby Championship for the first time this season with a bonus-point victory over the Scarlets at the RDS.
But the scoreline flattered the hosts, who, after a fast start, suddenly turned sluggish and laboured past a gamey if limited Welsh outfit.
Leo Cullen's side still did manage eight tries without playing anywhere near their best.
The Scarlets, who had won just one of four coming into the fixture, put up a stubborn resistance, and the frustration will be Leinster’s.
With Leinster welcoming back a host of Ireland front-liners, including new co-captains Garry Ringrose and James Ryan, following their World Cup exploits, this was always going to be a huge ask of the Scarlets, who had won just one of nine previous meetings between the sides.
And less than 30 seconds into mission: nigh impossible they managed to make life even harder when centre Johnny Williams saw yellow for a tip tackle on Ringrose; it could have been red but a sin-binning was deemed sufficient by referee Hollie Davidson.
Their intent clear from the start, Leinster scored their first in the fourth minute after Ryan turned over the ball in the tackle in midfield and off they went.
Ringrose, Max Deegan, Jamie Osborne, Sam Prendergast and Jamison Gibson-Park quickly played the ball before the out-half ran in for his first Leinster try.
Five minutes later they again had the chance to run from deep and after Jimmy O'Brien made yards on the flank the ball was recycled close to the Scarlets line and Gibson-Park's superb long pass found the Ireland wing who stepped inside Tomi Lewis to dot down.
Dwayne Peel’s side offered little resistance to this point and Deegan was on hand to grab Leinster’s third, barging over after Jordan Larmour danced close to the line and Osborne was stopped inches out.
But before Leinster could wrap up the inevitable bonus point, Scarlets did have something to say.
The ball was turned over close to the visitors’ line and a long clearance and lost Leinster lineout allowed Scarlets the territory to build a spell of pressure.
They stayed patient and Williams showed his power to dot down despite the best efforts of Joe McCarthy and man of the match Hugo Keenan.
That was enough to temporarily subdue the hosts, who had won three games from four to this point, and between a number of knock-ons and penalty concessions, found themselves camped in their own 22.
Thomas Clarkson’s jackal penalty momentarily lifted the admirable siege but Caelan Doris knocked on from the subsequent lineout and the half fizzled out with Leinster 19-5 up and in line for an earful from Cullen.
Whatever was said had no immediate effect, however, and amid errors from both sides the first spark of the second half came when Kieran Hardy dummied Gibson-Park at the back of a scrum before making 70 yards and only being denied their second try by a Keenan tackle.
The Ireland full-back soon showed his ability on the ball and a mazy run from inside his own half to the opposition 22 set up Ringrose for a run-in and the bonus point.
Prendergast kicked his third conversion before making way for Ross Byrne, while Tadhg Furlong and Dan Sheehan came on for Clarkson and Rónan Kelleher.
The 15,664 at the RDS weren't happy as more mistakes crept into the game; a seemingly lawless breakdown and offside line didn’t help the flow of the game, while the total penalty count at the end was 21.
But Scarlets were beginning to tire and quick hands by Furlong and Byrne close to the line set up Osborne, who stepped inside his man to score their fifth.
Fintan Gunne, the scrum-half on his first appearance for Leinster, fired out a pass before Jack Boyle barrelled over, with Byrne adding his second conversion.
Sheehan's powerful running added some impetus to proceedings and he was stopped short before Osborne finished smartly for his second try, again converted by Byrne with five minute to play.
Byrne’s score took him over the 1,000-point mark for the province before replacement Scott Williams went in the bin for a high tackle on Gunne.
Leinster did have the last say, however, and Deegan ran in for his second to move Leinster over the 50-point mark, a milestone that didn’t tell the whole story.
Leinster: Hugo Keenan; Jordan Larmour, Garry Ringrose (co-capt), Jamie Osborne, Jimmy O'Brien; Sam Prendergast, Jamison Gibson-Park; Andrew Porter, Rónan Kelleher, Thomas Clarkson; Joe McCarthy, James Ryan; Max Deegan, Josh van der Flier, Caelan Doris.
Replacements: Dan Sheehan, Jack Boyle, Tadhg Furlong, Ross Molony, Scott Penny, Fintan Gunne, Ross Byrne, Ciarán Frawley
Scarlets: Tom Rogers; Tomi Lewis, Jonathan Davies (capt), Johnny Williams, Ryan Conbeer; Charlie Titcombe, Kieran Hardy; Steff Thomas, , Shaun Evans, Harri O'Connor; Alex Craig, Jac Price; Ben Williams, Teddy Leatherbarrow, Carwyn Tuipulotu.
Replacements: Ryan Elias, Sam O'Connor, Wyn Jones, Morgan Jones, Iwan Shenton, Archie Hughes, Ioan Nicholas, Scott Williams.
Referee: Hollie Davidson (SRU)
