It's the final round of the United Rugby Championship regular season with three of the four Irish provinces already guaranteed to progress.
Leinster, Munster and Ulster will all go into the play-offs, while Connacht's season will end on Saturday afternoon.
It's all about seedings now with everyone except Leinster, who are safe in the top spot, playing for places and home advantage in the knock-out phases.
TV
Ulster v Cell C Sharks (Friday 7.35pm) and Leinster v Munster (Saturday 7.15pm) are live on TG4 and Premier Sports, while Connacht v Zebre (Saturday 5pm) is live on RTÉ2 and RTÉ Player.
RADIO
RTÉ Radio 1 will have live commentary on Leinster v Munster.
ONLINE
RTE.ie/sport will have live scoring and blogs across the weekend with match reports and reaction from the grounds. All games are live on URC TV.
WEATHER
Belfast is forecast to see light rain showers in about 13C, while Galway on Saturday afternoon will be overcast, with temperatures around 14C. Dublin, later on Saturday evening, expects cloudy conditions in 15C.
Listen to the RTÉ Rugby podcast on Apple Podcasts, Soundcloud, Spotify or wherever you get your podcasts.
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Ulster sit fifth in the table and take on third-placed Sharks, who are one point further ahead.
A win will guarantee a home quarter-final, while the number two ranking for a home semi-final is possible and would most likely require a victory for Ulster and losses for Munster and Stormers who lead in many of the tie-breakers.
Dan McFarland's men suffered back to back home losses in defeats to Toulouse and Munster, while they bounced back somewhat with a hard-fought 16-10 victory in Edinburgh the last time out.
The Sharks, who boast Lukhanyo Am, Makazole Mapimpi, Bongi Mbonambi, Thomas du Toit and Siya Kolisi among their number, have won their last three games, including matches with Leinster and Connacht.
It's a first ever meeting of the teams, while Ulster have won all five previous home games against South African opposition.
Ulster: Mike Lowry; Rob Baloucoune, James Hume, Stuart McCloskey, Ethan McIlroy; Billy Burns, John Cooney; Andrew Warwick, Rob Herring, Tom O'Toole; Alan O'Connor, Iain Henderson (capt); Marcus Rea, Nick Timoney, Duane Vermeulen.
Replacements: John Andrew, Eric O’Sullivan, Gareth Milasinovich, Kieran Treadwell, Matty Rea, Nathan Doak, Stewart Moore, Rob Lyttle.
Sharks: Aphelele Fassi; Werner Kok, Lukhanyo Am, Marius Louw, Makazole Mapimpi; Curwin Bosch, Jaden Hendrikse; Ox Nche, Bongi Mbonambi, Thomas du Toit (capt); Ruben van Heerden, Reniel Hugo; Siya Kolisi, Henco Venter, Phepsi Buthelezi.
Replacements: Kerron van Vuuren, Ntuthuko Mchunu, Khutha Mchunu, Hyron Andrews, Jeandre Labuschagne, Sikhumbuzo Notshe, Grant Williams, Boeta Chamberlain.
Referee: Ben Blain (SRU, 20th league game)
Connacht, with eight wins and nine defeats to date, have long been out of the play-off reckoning.
They are already looking to next season and will say goodbye to a number of players after this game, while Andy Friend hopes to add seven new men to his panel for the 2022/23 season.
Currently in 12th spot they can get to 11th with a win over the bottom side, Zebre.
They need to win and hope the Lions slip up away to the Dragons.
The Italians, meanwhile, have lost their last two matches, to Benetton and Cardiff and sit rock bottom after winning just once this season.
Paul Boyle, Caolin Blade, Bundee Aki and Mack Hansen have been ruled out for the hosts through injury.
Dylan Tierney-Martin is handed his first Connacht start at hooker, while there are also starts for Seán Masterson at openside flanker and Oran McNulty at full-back.
Centurions Denis Buckley and Finlay Bealham partner Tierney-Martin in the front row, while locks Gavin Thornbury and Niall Murray are paired together.
Masterson is accompanied in the back row by his brother Eoghan and Cian Prendergast at number 8.
Kieran Marmion and captain Jack Carty continue at 9 and 10 respectively, as do centres Tom Daly and Tom Farrell.
The side is completed by wingers Alex Wootton and John Porch.
Included on the bench are departing players Ultan Dillane, Abraham Papali'i and Sammy Arnold who will make their final appearances for the club if called upon.
Connacht: Oran McNulty; John Porch, Tom Farrell, Tom Daly, Alex Wootton; Jack Carty (capt), Kieran Marmion; Denis Buckley, Dylan Tierney-Martin, Finlay Bealham; Gavin Thornbury, Niall Murray; Eoghan Masterson, Seán Masterson, Cian Prendergast.
Replacements: Dave Heffernan, Matthew Burke, Jack Aungier, Ultan Dillane, Abraham Papali'i, Colm Reilly, Conor Fitzgerald, Sammy Arnold.
Zebre Parma: Lorenzo Pani; Asaeli Tuivuaka, Franco Smith Jr., Enrico Lucchin, Jacopo Trulla; Carlo Canna, Chris Cook; Danilo Fischetti, Luca Bigi, Eduardo Bello; David Sisi (capt), Andrea Zambonin; Luca Andreani, Iacopo Bianchi, Taina Fox-Matamua.
Replacements: Giampietro Ribaldi, Paolo Buonfiglio, Matteo Nocera, Leonard Krumov, Ross Vintcent, Nicolò Casilio, Alessandro Fusco, Junior Laloifi.
Referee: Adam Jones (WRU, 21st league game)
Leinster are already assured of top spot and the top seeding for the play-offs. The little matter of a Heineken Champions Cup final against La Rochelle in Marseille next Saturday means that they will use fringe players to take on Munster at the Aviva Stadium.
A win of any description will consolidate Munster's second place in the standings.
The 2011 champions are level with Cell C Sharks, DHL Stormers and Ulster with 11 games won so a try-bonus point victory could be key to earning number two ranking and securing a home semi-final (should they qualify).
Defeat, depending on how the Bulls do against Ospreys, could see Munster drop to sixth.
Munster have played not since the Champions Cup loss to Toulouse two weeks ago but prior to that beat Exeter, Cardiff and Ulster.
Leo Cullen welcomes back Ireland internationals Jordan Larmour and Ryan Baird from injury.
Larmour slots in at full-back with Rob Russell on his right and Rory O'Loughlin on his left.
The now-familiar pairing of Ciarán Frawley and Jamie Osborne are together in midfield again while there’s a first home start for Cormac Foley at scrum-half where he has Harry Byrne outside him.
In the pack, Ed Byrne will captain the side and is joined in the front row by Seán Cronin and Thomas Clarkson.
Joe McCarthy and Josh Murphy are the locks with the returning Baird, Scott Penny and Max Deegan completing the starting XV.
Meanwhile, Jack O'Donoghue will captain Munster, who make four changes to the side that faced Toulouse.
Thomas Ahern, Andrew Conway, Dan Goggin and John Ryan all come into the side and a positional switch sees Fineen Wycherley move to the back row.
Mike Haley starts at full-back, Conway returns from a knee injury for his first Munster appearance since January on the right wing and Keith Earls moves to the left wing.
Goggin and Chris Farrell start together in midfield with the half-back partnership of Conor Murray and Joey Carbery unchanged.
Josh Wycherley, Niall Scannell and Ryan pack down in the front row with Jean Kleyn and Ahern in the engine room.
Fineen Wycherley, Alex Kendellen and O’Donoghue complete the side, while Stephen Archer is unavailable due to illness.
Leinster: Jordan Larmour; Rob Russell, Jamie Osborne, Ciarán Frawley, Rory O'Loughlin; Harry Byrne, Cormac Foley; Ed Byrne (capt), Seán Cronin, Thomas Clarkson;; Joe McCarthy, Josh Murphy; Ryan Baird, Scott Penny, Max Deegan.
Replacements: John McKee, Peter Dooley, Cian Healy, Devin Toner, Alex Soroka, Ben Murphy, David Hawkshaw, Adam Byrne. Munster: Mike Haley; Andrew Conway, Chris Farrell, Dan Goggin, Keith Earls; Joey Carbery, Conor Murray; Josh Wycherley, Niall Scannell, John Ryan; Jean Kleyn, Thomas Ahern; Fineen Wycherley, Alex Kendellen, Jack O'Donoghue (capt).
Replacements: Diarmuid Barron, Jeremy Loughman, Keynan Knox, Jason Jenkins, Jack Daly, Craig Casey, Ben Healy, Rory Scannell.
Referee: Frank Murphy (IRFU, 62nd league game)
