18 May, 11:09
IRFU Chief Executive Philip Browne has issued a statement following confirmation of Ronan O'Gara's decision to retire from playing professional rugby.
Wicklow man Cullen partners Devin Toner in the second row with Sean O'Brien set to make his 30th European appearance in a back row that also features Shane Jennings and Jamie Heaslip.
Kevin McLaughlin misses the game with a shoulder knock but is expected to be available for the round 6 clash away to Exeter Chiefs.
The front row is unchanged from the side which started last weekend's bonus point victory over Edinburgh, so Cian Healy will make his 108th appearance for his home province alongside Sean Cronin and Mike Ross.
In the back-line, Isaac Boss partners Jonathan Sexton at half back with Gordon D'Arcy continuing in the centre alongside the returning Fergus McFadden who was rested last weekend.
Isa Nacewa is recalled to an experienced back-three which also features the fit-again Luke Fitzgerald and last season's European Player of the Year Rob Kearney.
Brian O'Driscoll, who made his comeback from injury in Edinburgh, is listed among the replacements alongside fellow Ireland internationals Michael Bent, Eoin Reddan and Rhys Ruddock.
LEINSTER (v Scarlets): Rob Kearney; Isa Nacewa, Fergus McFadden, Gordon D'Arcy, Luke Fitzgerald; Jonathan Sexton, Isaac Boss; Cian Healy, Sean Cronin, Mike Ross, Leo Cullen (capt), Devin Toner, Sean O'Brien, Shane Jennings, Jamie Heaslip.
Replacements: Aaron Dundon, Heinke van der Merwe, Michael Bent, Tom Denton, Rhys Ruddock, Eoin Reddan, Ian Madigan, Brian O'Driscoll.