Ian Madigan forms a new-lookg midfield pairing with Brian O'Driscoll, who will make his 83rd European appearance and now lies just four caps behind second-placed Shane Horgan on the province's all-time list.
Gordon D'Arcy is ruled out due to a calf strain but it is hoped that the Wexford man will fully recover in time for the league visit of the Ospreys next weekend.
The back row unit sees Jamie Heaslip partnering fellow Ireland internationals Shane Jennings and Kevin McLaughlin, while Cian Healy and Mike Ross form an all-Ireland front row alongside hooker Richardt Strauss.
Five of the Leinster replacements have come through the province's Academy. Saturday's game is a sell out and there will be no tickets on sale on the day.
This is a meeting between the 2012 Heineken Cup champions and Amlin Challenge Cup winners, with Leinster bidding to reach their fourth European final in the space of five seasons.
Biarritz qualified for the last-four with a 41-31 quarter-final victory away to Gloucester, and Brian O'Driscoll rates the French visitors highly.
"Biarritz are going to be tough opponents but we like to think we will be a handful ourselves. Looking at some of their video footage they look like a side who should be much further up the league than in 11th place in the Top 14," he said.
"We know they have got some very, very talented players - guys who we have known and played against for years.
"And any team that has managed to be in the Heineken Cup year after year coming out of the French league has to be pretty good going."
LEINSTER (Biarritz Olympique): Rob Kearney; Fergus McFadden, Brian O'Driscoll, Ian Madigan, Isa Nacewa; Jonathan Sexton, Isaac Boss; Cian Healy, Richardt Strauss, Mike Ross, Leo Cullen (capt), Devin Toner, Kevin McLaughlin, Shane Jennings, Jamie Heaslip.
Replacements: Sean Cronin, Jack McGrath, Jamie Hagan, Quinn Roux, Rhys Ruddock, John Cooney, Andrew Goodman, Andrew Conway.