Leinster have made two changes to the side which scraped to victory against Exeter Chiefs in the opening round of the Heineken Cup.
Geordan D'Arcy is named in the centres as he equals Shane Horgan's record European tally of 87 appearances.
Sean Cronin is named in Leinster's front row after impressing off the bench last week.
Gareth Maule replaces centre Jon Davies who is sidelined with a groin injury for the Scarlets.
Scarlets: Williams, North, Maule, Williams, Fenby, Priestland, Knoyle, John, Rees, Lee, Earle, Snyman, Shingler, Turnbull, McCusker
Leinster: Madigan, McFadden, O'Driscoll, D'Arcy, Nacewa, Sexton, Reddan, Healy, Cronin, Ross, Cullen, Browne, McLaughlin, Jennings, Heaslip
