Their places in the starting line-up have been taken by Tim Barker and Craig Gilroy, who have been promoted from from the replacements bench.
Neil McComb and Gilroy's Dungannon club-mate Conor Gaston have been added to the bench, with Darren Cave also providing back-up at the expense of Ian Whitten.
Ulster have won their previous six Magners League outings but have not beaten Leinster in Dublin since 1999.
Leinster defeated Leicester to progress to the semi-finals of the Heineken Cup last weekend but are not expected to rest many players for this crucial game.
The Ulstermen currently occupy second position in the league table, three points ahead of their fourth-placed Irish rivals.
Defeat for either team would be a major setback as both provinces are chasing a play-off spot.
ULSTER (v Leinster): Adam D'Arcy; Andrew Trimble, Nevin Spence, Paddy Wallace, Craig Gilroy; Ian Humphreys, Ruan Pienaar; Tom Court, Rory Best (capt), BJ Botha, Tim Barker, Dan Tuohy, Robbie Diack, Chris Henry, Pedrie Wannenburg.
Replacements: Andi Kyriacou, Paddy McAllister, Bryan Young, Neil McComb, Willie Faloon, Paul Marshall, Darren Cave, Conor Gaston.