The four provincial sides confirmed their matchday lineups ahead of a busy opening weekend across Europe's top club competitions.
Ulster will face Italian side Zebre in the Challenge Cup at 15:15 BST, seeking to recover from last season's defeat by Montpellier in the final.
Four players are set to make their debut for Ulster in the Champions Cup, including fly-half Charlie O'Shea and back row Sean Edogbo who start alongside Max Clein and Ben O'Donovan on the bench.
In the Investec Champions Cup, last year's runners-up Leinster travel to France to play Clermont Auvergne at 15:15 BST.
Connacht host Saracens in Derry at 17:30 while Munster welcome Racing 92 to Cork for a match starting at 20:00.
Joey Carbery is scheduled to feature in Leinster's squad, marking his first appearance with the province since 2018 after spells at Munster and Bordeaux.
Head coach Leo Cullen has selected Sam Prendergast at fly-half while Dan Sheehan captains a strong starting XV featuring fourteen Ireland internationals.
The forward pack includes Andrew Porter and Tadhg Furlong in the first row with Joe McCarthy and James Ryan in the second, joined by an experienced back row of Ryan Baird, Josh van der Flier and Jack Conan.