Harry Byrne starts at out-half for Leinster's trip to the Ospreys, Finlay Bealham and Mack Hansen are back for Connacht's crunch game with the Cell C Sharks, while Robert Baloucoune makes his 50th appearance for Ulster at Benetton.
Ireland wing Baloucoune reaches his half-century for Ulster when they travel to Treviso on Saturday (kick-off 1pm Irish time).
The 25-year-old, who made a try-scoring return from injury in the New Year's Day defeat to Munster, forms an all-international back three with Mike Lowry and Jacob Stockdale.
The last-gasp loss to Munster was Ulster’s fourth defeat in five matches and head coach Dan McFarland has made five changes for the trip to Treviso.
Lowry replaces Stewart Moore at full-back in the only backline alteration, while Eric O’Sullivan, Rob Herring and Jeff Toomaga-Allen form a new-look front row.
Skipper Iain Henderson is partnered by fellow Ireland lock Kieran Treadwell in the second row, with Nick Timoney preferred to Duane Vermeulen at No 8.
With tighthead prop Marty Moore facing a lengthy spell on the sidelines with a knee injury, Ulster have named two looseheads on the bench in Rory Sutherland and Andy Warwick.
Ulster: Mike Lowry; Robert Baloucoune, James Hume, Stuart McCloskey, Jacob Stockdale; Billy Burns, John Cooney; Eric O’Sullivan, Rob Herring, Jeff Toomaga-Allen; Kieran Treadwell, Iain Henderson (capt); Greg Jones, Sean Reffell, Nick Timoney.
Replacements: Tom Stewart, Rory Sutherland, Andy Warwick, Alan O’Connor, Duane Vermeulen, Nathan Doak, Stewart Moore, Ethan McIlroy.
Connacht welcome back Ireland internationals Finlay Bealham and Mack Hansen for their crucial game against the Cell C Sharks, live on RTÉ2 and RTÉ Player from 4.45pm (kick-off 5.15pm).
Bealham, Hansen and Josh Murphy are restored to the starting line-up after recovering from illness but Bundee Aki is not included in the match-day 23.
Andy Friend makes nine changes to the team that lost to Leinster on New Year's Day with Kieran Marmion coming in to partner captain Jack Carty at half-back.
Cathal Forde replaces the injured David Hawkshaw at inside centre while John Porch switches wings to accommodate Hansen’s inclusion on the left.
Darragh Murray and Shamus Hurley-Langton are the only players retained in the pack, the latter moving to No 8 as Conor Oliver comes in at openside.
Oisín Dowling partners Murray in the second row, packing down behind Denis Buckley, Shane Delahunt and Finlay Bealham.
Connacht: Tiernan O’Halloran; John Porch, Tom Farrell, Cathal Forde, Mack Hansen; Jack Carty (capt), Kieran Marmion; Denis Buckley, Shane Delahunt, Finlay Bealham; Oisín Dowling, Darragh Murray; Josh Murphy, Conor Oliver, Shamus Hurley-Langton.
Replacements: Dylan Tierney-Martin, Jordan Duggan, Dominic Robertson-McCoy, Leva Fifita, Cian Prendergast, Caolin Blade, Conor Fitzgerald, Byron Ralston.
Harry Byrne makes his first start of the season as URC leaders Leinster travel to the Ospreys (kick-off 7.35pm) seeking a 14th successive win in all competitions.
Byrne is named at out-half alongside Cormac Foley as Leo Cullen makes 10 changes to the team that extended their 100% start to the season against Connacht.
Hugo Keenan returns at full-back so Jimmy O’Brien moves to the left wing while Jamie Osborne partners Charlie Ngatai in the midfield.
Cian Healy and Dan Sheehan come into the front row with Ross Molony named alongside Brian Deeny in the second row.
It is all change the back row where captain Rhys Ruddock is joined by Scott Penny and Jack Conan, while James Ryan and Josh van der Flier will provide impact from the bench.
Leinster: Hugo Keenan; Jordan Larmour, Jamie Osborne, Charlie Ngatai, Jimmy O’Brien; Harry Byrne, Cormac Foley; Cian Healy, Dan Sheehan, Michael Ala’alatoa; Ross Molony, Brian Deeny; Rhys Ruddock (capt), Scott Penny, Jack Conan.
Replacements: John McKee, Michael Milne, Vakhtang Abdaladze, James Ryan, Josh van der Flier, Nick McCarthy, Ross Byrne, Rob Russell.
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Watch live coverage of Connacht v Sharks (Saturday, 5.15pm) in the BKT United Rugby Championship on RTÉ2 and RTÉ Player.
