Leinster, Munster, Connacht and Ulster are all playing
Eadestown's Jimmy O'Brien will start for Leinster in their Champions Cup game against Sale Sharks at the RDS tomorrow night.
Suncroft's Sam Prendergast has been named among the replacements.
Munster play Exeter Chiefs on Sunday afternoon and Athy's Jeremy Loughman and Eadestown's Tadhg Beirne are both down to start.
Suncroft's Cian Prendergast starts for Connacht against Saracens.
Eadestown's Diarmuid Kilgallen is among the replacements.
Finally, Celbridge's Marty Moore is on the bench for Ulster, who play Racing 92.