It's the final round of regulation games before the Leinster-Munster decider on 27 March.
Devin Toner will win his 261st cap for Leinster and so equal Gordon Darcy's all-time record when he lines up to face the Ospreys in Friday's Guinness Pro14 clash at the RDS, kick-off 8.15pm.
Toner, who made his debut for the province in 2006, will start alongside Ross Molony in the second row.
Scott Fardy will captain the side from the back row. Max O'Reilly again starts at full back with Dave Kearney continuing on the left wing after his hat-trick of tries last weekend against Zebre.
Guinness Player of the Match from that same game in Italy, Rory O'Loughlin, moves to the right wing this week with Cian Kelleher missing out through injury.
It's a new centre partnership this week for Cullen with Skerries RFC man Ciarán Frawley back from injury to partner Naas RFC's Jamie Osborne. It will be Osborne's second start for Leinster
In the pack Peter Dooley will win his 90th cap for the province when he lines up alongside Séan Cronin, who is back from injury, and Michael Bent in the front row.
On the bench Seán O'Brien and Tim Corkery will experience a game at the RDS Arena for the first time after their successful debuts off the bench against Zebre last weekend. It will also be Clane RFC man Marcus Hanan's first experience of the RDS.
At Thomond Park, Munster take on Benetton at 6pm. There will be a senior debut for Garryowen's Cian Hurley with Diarmuid Barron, Jake Flannery and Paddy Patterson all making their first Munster starts.
Four Greencore Munster Rugby Academy players are set to feature as Thomas Ahern and Flannery both start with Jack Daly and Ben Healy among the replacements.20-year-old Clonakilty man Hurley makes his Munster debut in the second row. A product of Clonakilty RFC and CBC, Hurley has made five appearances for Munster A this season and is a member of the National Talent squad.
Andrew Conway and Liam Coombes join Flannery in the back three with Rory Scannell and Alex McHenry forming the centre partnership.
Patterson and JJ Hanrahan start in the half-backs.Liam O'Connor, Barron and Keynan Knox pack down in the front row with Hurley and Ahern in the second row. Captain Jack O’Donoghue, Chris Cloete and Jack O’Sullivan complete the side.
Munster: Jake Flannery; Andrew Conway, Alex McHenry, Rory Scannell, Liam Coombes; JJ Hanrahan, Paddy Patterson; Liam O'Connor, Diarmuid Barron, Keynan Knox; Cian Hurley, Thomas Ahern; Jack O’Donoghue (C), Chris Cloete, Jack O’Sullivan.
Replacements: Rhys Marshall, Jeremy Loughman, Roman Salanoa, Jack Daly, Tommy O’Donnell, Nick McCarthy, Ben Healy, Matt Gallagher.
Leinster: Max O'Reilly; Rory O’Loughlin, Jamie Osborne, Ciarán Frawley, Dave Kearney; Harry Byrne Rowan Osborne; Peter Dooley, Seán Cronin, Michael Bent; Ross Molony, Devin Toner; Scott Fardy (Capt) Scott Penny, Josh Murphy
Replacements: Dan Sheehan, Marcus Hanan, Thomas Clarkson, Jack Dunne, Seán O’Brien, Hugh O’Sullivan, Tim Corkery, Alex Soroka.
21-year-old, Cormac Izuchukwu will make his first start for Ulster as he is named in the second row alongside Kieran Treadwell in the team to play Zebre at the Kingspan Stadium, kick-off 8.15pm.
Marty Moore comes back into the starting front row at tighthead, with Eric O’Sullivan and John Andrew retaining their starting berths at loosehead and hooker. Jordi Murphy will captain the side at openside flanker, with Sean Reidy and David McCann being retained at blindside and No 8.
A youthful back line sees Ethan McIlroy coming into the back three at full-back, with Rob Lyttle on the left wing and Robert Baloucoune returning on the right. Stewart Moore and James Hume will make up the midfield pairing, while John Cooney and Michael Lowry are named at half-back.
Brad Roberts, Callum Reid, Tom O’Toole, Alan O’Connor and Matty Rea are the forward reinforcements, with David Shanahan, Ian Madigan and Ben Moxham providing the back line options on the bench.
Ulster: Ethan McIlroy; Robert Baloucoune, James Hume, Stewart Moore, Rob Lyttle; Michael Lowry, John Cooney; Eric O’Sullivan, John Andrew, Marty Moore; Cormac Izuchukwu, Kieran Treadwell; Sean Reidy, Jordi Murphy (Capt), David McCann.
Replacements: Brad Roberts, Callum Reid, Tom O’Toole, Alan O’Connor, Matty Rea, David Shanahan, Ian Madigan, Ben Moxham.
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