Leinster started with 10 of Ireland's World Cup squad as they routed Scarlets 54-5 in the United Rugby Championship.

Max Deegan's try extended the lead to 19-0 before Williams regrouped from his yellow card to score before the break.

Jamie Osborne notched two second-half tries for the home side with Deegan scoring again as Garry Ringrose and Jack Boyle also touched down.

Leinster boss Leo Cullen was able to call upon his Ireland contingent at the RDS as Hugo Keenan, Ringrose, O'Brien, Jamison Gibson-Park, Andrew Porter, Ronan Kelleher, Joe McCarthy, James Ryan, Josh van der Flier and Caelan Doris went straight into the starting XV, while three of their international colleagues made the bench.

Referee Hollie Davidson had a visit to the TMO screen after just 30 seconds and she sent Scarlets' Williams to the bin for a tip tackle on Ringrose.

The hosts immediately took advantage as fly-half Prendergast touched down after good hands from Osborne.

Prendergast was unable to convert his try but did slot the extras after wing O'Brien went over in the left corner following a wide pass flung from Gibson-Park.

The third score was straight out of the Leinster playbook with Deegan eventually crashing over from close range for a seven-pointer after a strong lineout maul and slick passing which saw Jordan Larmour making ground.

Dwayne Peel's men did come back into the game before the break as Williams somewhat made up for his early ill-discipline by barging his way over in the corner for a score that debutant fly-half Charlie Titcombe could not convert.

Leinster wrapped up a bonus point 10 minutes into the second half as Ringrose put the finishing touches to a breakaway following a Jonathan Davies knock-on.

That opened the floodgates as Cullen utilised his incredibly strong bench with replacements Tadhg Furlong and Ross Byrne initially setting up Osborne's first try.

Another replacement, Boyle, burrowed over for Leinster's sixth touchdown before Osborne and Deegan brought up the points half-century as both notched their second tries, following the yellow-carding of Scarlets replacement Scott Williams.

The win was Leinster's fourth in a row and sets them up nicely for a huge clash with Munster at the Aviva Stadium next weekend, while Scarlets are second from bottom in the table after earning only one victory in their opening five games.

Leinster: Keenan; Larmour, Ringrose (co-capt), Osborne, J O'Brien; Prendergast, Gibson-Park; Porter, Kelleher, Clarkson; McCarthy, Ryan (co-capt); Deegan, Van der Flier, Doris.

Replacements: Sheehan, Boyle, Furlong, Molony, Penny, Gunne, R Byrne, Frawley.

Scarlets: Rogers; Lewis, Davies (capt), J Williams, Conbeer; Titcombe, Hardy; W Jones, Evans, O'Connor; Craig, Price; B Williams, Leatherbarrow, Tuipulotu.

Replacements: Elias, Thomas, Wainwright, M Jones, Shenton, Hughes, Nicholas, S Williams.

Referee: Hollie Davidson (SRU)