Leinster, Munster, Ulster and Connacht have all named their teams ahead of this weekend's games
Munster have been boosted by the return of Peter O’Mahony for their trip to Northampton in the Investec Champions Cup tomorrow.
Eadestown's Diarmuid Kilgallen makes his competitive debut on the wing, while Diarmuid Barron comes into the pack.
The winners of the match will earn a home tie in the round of 16 in April.
Hugo Keenan returns to the Leinster team at full-back for their match against Bath tomorrow evening.
Leo Cullen has made five changes from last week's win at La Rochelle as the URC table toppers seek a win that would secure home advantage in the knockout stages.
Props Andrew Porter and Rabah Slimani, and back-rows Max Deegan and Jack Conan come into the pack with Conan captaining the team.
Connacht head coach Pete Wilkins has made four changes for tomorrow's trip to Cardiff in the Challenge Cup.
Byron Ralston starts on the wing, while Josh Murphy, Conor Oliver and Paul Boyle come into the pack.
The fit-again JJ Hanrahan is set to make his long-awaited return to the pitch after being named among the replacements.
Ulster need a bonus-point against Exeter this evening if they're to have a chance of sneaking into the knockout stages of the Investec Champions Cup.
Richie Murphy's team would also need the Sharks to lose at Bordeaux on Sunday, but a win for Ulster tonight would see them drop into the Challenge Cup.
There's a 8pm kick-off at Kingspan Stadium.
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