All four provinces are in United Rugby Championship action this weekend.
A knee injury has ruled Bundee Aki out of Connacht's inter-pro derby with Ulster tomorrow.
The Lions centre will sit out the game at the Aviva Stadium in the United Rugby Championship but is still set to link up with the Ireland squad.
Tom Daly replaces Aki in Connacht's midfield with Athlone's Jack Carty and Niall Murray also both set to start.
Ulster are boosted by the return of their captain Iain Henderson.
Fellow Ireland internationals Robert Baloucoune, Stuart McCloskey and Eric O'Sullivan also come in to start.
Conor Murray and Damien de Allende both get their first starts of the campaign for Munster for their trip to Ospreys.
It all starts with Leinster's trip to Glasgow this evening.
7.35 is the throw-in time in Scotstoun.
Jonathan Sexton’s been given a chance to recover from a hip injury ahead of Ireland’s autumn internationals.
He’s been omitted from the Leinster matchday squad, Luke McGrath captains, in his absence, from scrum-half.
🟢 TEAM ANNOUNCEMENT 🟢
— Connacht Rugby (@connachtrugby) October 22, 2021
Here's our matchday squad for tomorrow's historic #URC clash with @UlsterRugby at the Aviva Stadium!#CONvULS #StrengthInNumbers
Full story: https://t.co/eacRK14W9k
Tickets: https://t.co/jONuehDExl pic.twitter.com/0dKW9220xh
Westmeath SFC: Coralstown Kinnegad Manager Proud Of His Team's Efforts
13 Medals For Team Ireland At European U15 Championships
Offaly SFC: Agony For Ferbane Once Again
Westmeath SFC: The Down's Show Their Class To Win Championship
Portlaoise Panthers Keep Up 100% Record
Laois SFC: Portarlington Make It Five Titles In Six Years
Enda Rowland Announces Reitrement From Inter-County Hurling
Buccaneers End Losing Streak With Away Win Against Enniscorthy
Offaly SFC: Three In A Row Secured For Tullamore
Portlaoise Panthers Suffer Defeat In Women's Super League
Westmeath SHC: Back To Back Titles For Castletown Geoghegan
Westmeath SHC: Ending Championship Drought On The Cards For Lough Lene Gaels
Laois SFC: Consistency The Message From Portarlington Manager
Portlaoise Panthers Aiming To Return To Winning Ways
Westmeath SHC: Castletown Geoghegan And Lough Lene Gaels Set For Bank Holiday Clash
Buccaneers Travel To Wexford In AIL This Weekend
Laois SFC: A Second Chance Awaits Courtwood
Portlaoise Panthers Looking To Continue 100% Start