Peter Robb will make his Pro12 debut for leaders Connacht while Luke Fitzgerald returns for Leinster for Saturday's top-of-the-table contest.
Connacht's two changes from the win over Edinburgh see Robb, 21, and Niyi Adeolokun replacing Craig Ronaldson and Danie Poolman in the backs.
Ireland centre Robbie Henshaw is named in the Connacht replacements.
Fitzgerald's inclusion after injury is one of eight Leinster changes from last Friday's defeat by Glasgow. The wing missed Ireland's entire Six Nations campaign because of a medial ligament injury.
Fitzgerald is joined in the backline by Ian Madigan and Fergus McFadden who both featured as replacements in Ireland's win over Scotland.
Richardt Strauss, Cian Healy and Rhys Ruddock will also start for Leinster in Galway after being introduced by Ireland last weekend while another of Joe Schmidt's Six Nations players Josh van der Flier is named in the back row.
A strong Leinster bench includes Ireland players Jamie Heaslip, Jack McGrath, Mike Ross, Devin Toner, Sean Cronin and Eoin Reddan.
Henshaw is joined in the Connacht replacements by another Ireland squad member Finlay Bealham.
Nathan White, who featured in all five of Ireland's Six Nations games, will start in the Connacht front row while youngster Sean O'Brien is again named in the back row alongside Jake Heenan and skipper John Muldoon.
Connacht go into the Sportsground contest a point ahead of Leo Cullen's Leinster side.
T O'Halloran; N Adeolokun, B Aki, P Robb, M Healy; AJ MacGinty, K Marmion; D Buckley, T McCartney, N White; Q Roux , A Muldowney; S O'Brien, J Heenan, J Muldoon (capt)
Replacements: D Heffernan, R Loughney, F Bealham, A Browne, E McKeon, C Blade, S O'Leary, R Henshaw.
I Nacewa (capt); F McFadden, G Ringrose, B Te'o, L Fitzgerald; I Madigan, L McGrath; C Healy, R Strauss, T Furlong; R Molony, H Triggs; D Ryan, J van der Flier, R Ruddock
Replacements: S Cronin, J McGrath, M Ross, D Toner, J Heaslip, E Reddan, N Reid, Z Kirchner