In-form Leinster take on Scarlets in the RaboDirect PRO12 on Saturday, while Treviso host Cardiff Blues and Zebre entertain Ulster.
Leinster now sit third in the table, having won their last five contests in all competitions. Boss Matt O'Connor has made nine changes as he calls upon several members of the Ireland squad who were involved in the recent November Tests.
Gordon D'Arcy partners Brendan Macken at centre, Eoin Reddan links up with Ian Madigan at half-back, with Luke Fitzgerald - who is one of eight Ireland internationals in the starting XV - named in an exciting back three alongside South African international Zane Kirchner and former Wallaby Lote Tuqiri.
Leo Cullen will make his seasonal debut for the province and is named at lock alongside Mike McCarthy.
Jack McGrath starts in the front row alongside Aaron Dundon and Martin Moore. Shane Jennings leads the side and is named in the back-row alongside Academy graduates Rhys Ruddock and Jordi Murphy.
Meanwhile, Scarlets boss Simon Easterby has made just two changes to his run-on side.
Scottish international John Barclay returns back to his regional shirt in the back row with Jo Synman coming in for George Earle in the second row, with the former sidelined with concussion.
Rob Evans (prop) and Jordan Williams (wing) are released back from international training with Wales to come onto the bench and Romanian giant Horatiu Pungea also returns from national duty.
Ulster boss Mark Anscombe has made seven changes to the team that beat Edinburgh for the visit to Zebre.
Ricky Andrew starts at full-back in place of Craig Gilroy, who moves to the left wing. Andrew Trimble continues on the right wing, alongside Darren Cave and Luke Marshall, who keep their places in midfield.
Ireland fly-half, Paddy Jackson, returns to the Ulster line up and is partnered by Paul Marshall in the half-back roles. Up front, Tom Court is selected at loosehead, with Callum Black moving to the bench.
With injuries to both Lewis Stevenson (medial ligament) and Iain Henderson (hamstring), there is a new second row, with Neil McComb selected alongside Dan Tuohy.
Robbie Diack captains the side from blindside flanker with Mike McComish named at openside and Roger Wilson starting at Number 8. Tommy Bowe and Ruan Pienaar are rested for the match.
Meanwhile, Zebre start with a highly-experienced second-row pairing of Quentin Geldenhuys and Marco Bortolami.
In the front-row, hooker Tommaso D'Apice is joined by Matias Aguero and David Ryan, while returning Italy fly-half Luciano Orquera is named among the substitutes.
In the last of Saturday's games, Owen Jenkins and Ellis Jenkins are both handed first-ever Pro12 starts as Cardiff Blues tackle Treviso.
Cardiff director of rugby Phil Davies makes a total of six changes to the side that was defeated by leaders Munster.
Hooker Rhys Williams makes his first start of the season and Filo Paulo returns in the second row after international duty with Samoa. Macauley Cook moves into the back row.
Fly-half Gareth Davies returns to the starting line-up and Dan Fish is fit again to take his place at full back.
Prop Scott Andrews misses the game through injury and scrum half Lloyd Williams with illness after returning from Wales duty.
Treviso have named a new centre pairing of Christian Loamanu and Michele Campagnaro. In the back row, openside flanker Dean Budd is called up to join the formidable duo of Manoa Vosawai and Alessandro Zanni.