With just three rounds of the Pro12 left to play, only the top five teams can now make the play-offs.
However, with qualification for next season’s European Champions Cup based on meritocracy, there is something to play for in every match this weekend.
The action kicks off with perhaps the most eagerly anticipated game of the round at the Kingspan Stadium in Belfast – hosts Ulster need every point if they are to claim a home draw in the Pro12 play-offs.
This really is a must-win match for visitors Leinster. If they lose and should other results go against them, they could be out of contention for the last four for the first time.
Also on Friday Challenge Cup finalists Edinburgh are one of three teams battling for automatic qualification to the top tier of next season’s European competition, whilst Zebre are closing in on Benetton Treviso in the race to claim the Italian spot and must be hoping their hosts attention will be focused elsewhere.
All eyes in Wales will be on the "Judgement Day" double-header at the Millennium Stadium on Saturday.
Ospreys need a win over Cardiff Blues to keep up their challenge to make the final four of the Pro12, whilst Scarlets can still claim automatic qualification to the Champions Cup next season, victory over Newport Gwent Dragons is therefore essential.
Scarlets vice-captain Scott Williams has said it's vitally important for Scarlets to win their remaining three games to secure a European place next season. It will be a tough challenge, with the first of those three obstacles against the Dragons on "Judgement Day".
"Dragons have been playing well and they'll be raring to go but we've got a couple of things to put right as well so hopefully it'll be a good spectacle. We have to make sure we're on our toes now," Williams said.
"It's going to be tough [winning the next three matches] but it's definitely a goal we can reach.
"All we can do is make sure we get as much points as we can out of the last three games and hopefully that will be enough."
Another team with European qualification on their mind, Connacht, find themselves in action against league leaders Glasgow on Saturday.
The Warriors are looking for every point to claim top seed in the play-offs and Connacht knowing both Scarlets and Edinburgh are making advances on the sixth placed spot they’ve held since Round Seven.
And finally Munster, who are in second place thanks only to a better points difference than fellow Irish province Ulster, will be looking to consolidate their advantage with a win over Benetton Treviso, which will be no easy task as the Italians are also looking towards next season’s Champions Cup qualification.
We look at all the Round 20 matches.
Friday, April 24
Edinburgh v Zebre (Murrayfield, Edinburgh – Kick-off: 19.35; 18.35 GMT)
Edinburgh, who became the first Scottish side ever to reach a European Cup final at the weekend, have lost just one of their last five encounters in all tournaments: 3-34 at home to Munster in the Pro12 in April.
Edinburgh have lost their last two Pro12 matches at Murrayfield since beating Glasgow there in the 1872 Cup game in January. Zebre’s only victory in the Pro12 since November was 23-17 at home to Newport Gwent Dragons in Round 16. The Italians have recorded only one away victory in their three seasons of Pro12 participation – at Cardiff Blues in September 2013.
The two sides have met on five previous occasions with Edinburgh taking the first three and Zebre the most recent two, only one of those encounters being an away victory: 9-7 by Edinburgh in Parma in March 2013. The only Italian club side to have won at Murrayfield is Benetton Treviso in the Pro12 in October 2012.
Teams:
Edinburgh: 15 Tom Brown, 14 Dougie Fife, 13 Sam Beard 12 Andries Strauss, 11 Tim Visser, 10 Phil Burleigh, 9 Sam Hidalgo-Clyne, 8 Mike Coman (captain), 7 Roddy Grant, 6 Stuart McInally, 5 Ben Toolis, 4 Anton Bresler, 3 WP Nel, 2 Ross Ford, 1 Alasdair Dickinson.
Replacements: 16 Neil Cochrane, 17 Rory Sutherland, 18 John Andress, 19 Fraser McKenzie, 20 Cornell du Preez, 21 Nathan Fowles, 22 Tom Heathcote, 23 Carl Bezuidenhout.
Zebre: 15 Hendrik Daniller, 14 Giulio Toniolatti, 13 Mirco Bergamasco, 12 Gonzalo Garcia, 11 David Odiete, 10 Luciano Orquera, 9 Guglielmo Palazzani, 8 Samuela Vunisa, 7 Andries Van Schalkwyk, 6 Filippo Cristiano, 5 Marco Bortolami (captain), 4 Valerio Bernabò, 3 Dario Chistolini, 2 Andrea Manici, 1 Matias Aguero.
Replacements: 16 Oliviero Fabiani, 17 Andrea Lovotti, 18 Luca Redolfini, 19 Andrei Mahu, 20 Filippo Ferrarini, 21 Alberto Chillon, 22 Matteo Pratichetti, 23 Brendon Leonard.
Referee: Leighton Hodges (Wales)
Assistant Referees: Mike Adamson (Scotland), Stephen Hart (Scotland)
TMO: Jim Yuille (Scotland)
Ulster v Leinster (Kinspan Stadium, Belfast – Kick-off: 19.35; 18.35 GMT)
Ulster’s only defeat in their last seven Pro12 matches was 22-26 to the Dragons in Newport in Round 17, whilst the 24 league points picked up in their last six matches is the best tally of any side in that period.
Ulster have won all nine Pro12 games played in Belfast this season with their most recent defeat at the venue in the tournament being when Leinster were the visitors in Round 21 last year.
Leinster ‘s only win in their last six matches in all competitions was 18-15 over Bath in the quarterfinal of the Champions Cup on April 4, whilst their single victory in their last six Pro12 encounters came at home to Zebre in Round 15.
Leinster have won their last five fixtures against Ulster, although four of these have been played at the RDS Arena. The Leinstermen have lost on just two of their last ten visits to Kingspan Stadium.
Teams:
Ulster: 15 Louis Ludik, 14 Tommy Bowe, 13 Jared Payne, 12 Darren Cave, 11 Craig Gilroy, 10 Paddy Jackson, 9 Ruan Pienaar, 8 Roger Wilson, 7 Chris Henry, 6 Iain Henderson, 5 Franco van der Merwe, 4 Dan Tuohy, 3 Wiehahn Herbst, 2 Rory Best (captain), 1 Callum Black.
Replacements: 16 Rob Herring, 17 Andrew Warwick, 18 Bronson Ross, 19 Robbie Diack, 20 Clive Ross, 21 Paul Marshall, 22 Ian Humphreys, 23 Stuart McCloskey.
Leinster: 15 Rob Kearney, 14 Zane Kirchner, 13 Ben Te'o, 12 Gordon D'Arcy, 11 Luke Fitzgerald, 10 Jimmy Gopperth, 9 Isaac Boss, 8 Jamie Heaslip (captain), 7 Sean O'Brien, 6 Dominic Ryan, 5 Mike McCarthy, 4 Devin Toner, 3 Mike Ross, 2 Richardt Strauss, 1 Cian Healy.
Replacements: 16 Sean Cronin, 17 Jack McGrath, 18 Tadhg Furlong, 19 Ben Marshall, 20 Jordi Murphy, 21 Eoin Reddan, 22 Ian Madigan, 23 Darragh Fanning.
Referee: John Lacey (Ireland)
Assistant Referees: Leo Colgan (Ireland), Olly Hodges (Ireland)
TMO: Seamus Flannery (Ireland)
Saturday, April 25
Connacht v Glasgow Warriors (Galway Sportsground, Galway – Kick-off: 13.05; 12.05 GMT)
Connacht have slipped to defeat in their last four fixtures in all competitions since beating Benetton Treviso 53-5 in Galway in the Pro12 in March. The Irishmen have won only two of their last eight contests against Scottish opponents.
Glasgow Warriors’ only defeat in their last six Pro12 fixtures was 10-22 to Munster in Cork in Round 16, whilst they have tallied a try bonus point in each of their last three matches.
Away from home it is a different story, with their solitary win in their last seven trips in all tournaments was on a visit to Zebre in the Pro12 in February.
Connacht have not beaten Glasgow since a 37-8 scoreline was obtained at the Sportsground in February 2011, subsequently there has been a draw (in February 2012) and six successive Warrior victories.
Teams:
Connacht: 15 Tiernan O'Halloran, 14 Danie Poolman, 13 Robbie Henshaw, 12 Bundee Aki, 11 Matt Healy, 10 Jack Carty, 9 Kieran Marmion, 8 Eoin McKeon, 7 Eoghan Masterson, 6 John Muldoon (captain), 5 Aly Muldowney, 4 Ultan Dillane, 3 Rodney Ah You, 2 Tom McCartney, 1 Denis Buckley
Replacements: 16 Shane Delahunt, 17 Ronan Loughney, 18 Finlay Bealham, 19 Andrew Browne, 20 George Naoupu, 21 John Cooney, 22 Miah Nikora, 23 Darragh Leader.
Glasgow Warriors: 15 Stuart Hogg, 14 Tommy Seymour, 13 Richie Vernon, 12 Peter Horne, 11 Niko Matawalu, 10 Finn Russell, 9 Henry Pyrgos, 8 Adam Ashe, 7 Chris Fusaro, 6 Rob Harley, 5 Jonny Gray (Captain), 4 Leone Nakarawa, 3 Euan Murray , 2 Fraser Brown, 1 Jerry Yanuyanutawa.
Replacements: 16 Kevin Bryce, 17 Ryan Grant, 18 Jon Welsh, 19 Tim Swinson, 20 Josh Strauss, 21 Duncan Weir, 22 Peter Murchie, 23 Lee Jones.
Referee: Marius Mitrea (Italy)
Assistant Referees: Andy Brace (Ireland), Oisin Quinn (Ireland)
TMO: Dermot Moloney (Ireland)
Cardiff Blues v Ospreys (Millennium Stadium, Cardiff – Kick-off: 14.30; 13.30 GMT)
Cardiff Blues have won just two of their last seven Pro12 encounters – over Edinburgh and Connacht at the Arms Park in March. This is the Blues fourth Pro12 encounter at Millennium Stadium with the only loss being to Ospreys on "Judgement Day" two years ago.
Ospreys have won their last three Pro12 matches and have not been defeated in the tournament since a trip to the table-topping Warriors in Round 15. Osprey have made four previous visits to Millennium Stadium in all competitions and won them all – two in semifinals of the Anglo-Welsh Cup in 2007 and 2008, and their "Judgement Day" encounter for the past two years.
Ospreys have won their last seven encounters with The Blues in the Pro12 since the capital side’s 27-25 victory at the Cardiff City Stadium on New Year’s Eve 2010.
The two regions have met twice before at Millennium Stadium with Ospreys victorious 27-10 in the Anglo-Welsh Cups semifinal in March 2007, and 23-16 at "Judgement Day" six years later.
Teams:
Cardiff Blues: 15 Rhys Patchell, 14 Lucas Amorosino, 13 Tom Isaacs, 12 Garyn Smith, 11 Joaquin Tuculet, 10 Gareth Anscombe, 9 Lloyd Williams, 8 Josh Navidi, 7 Sam Warburton, 6 Josh Turnbull, 5 Filo Paulo, 4 Chris Dicomidis, 3 Craig Mitchell, 2 Kristian Dacey, 1 Gethin Jenkins (captain).
Replacements: 16 Matthew Rees, 17 Sam Hobbs, 18 Scott Andrews, 19 Jarrad Hoeata, 20 Macauley Cook, 21 Lewis Jones, 22 Gareth Davies, 23 Dan Fish.
Ospreys: 15 Dan Evans, 14 Tom Grabham, 13 Ben John, 12 Josh Matavesi, 11 Eli Walker, 10 Dan Biggar, 9 Rhys Webb, 8 Dan Baker, 7 Justin Tipuric, 6 Dan Lydiate, 5 Alun Wyn Jones (captain), 4 Lloyd Peers, 3 Aaron Jarvis, 2 Scott Baldwin, 1 Nicky Smith.
Replacements: 16 Sam Parry, 17 Marc Thomas, 18 Dmitri Arhip, 19 Tyler Ardron, 20 James King, 21 Tom Habberfield, 22 Sam Davies, 23 Jonathan Spratt.
Referee: Nigel Owens (Wales)
Assistant Referees: Rhys Thomas (Wales), Gwyn Morris (Wales)
TMO: Gareth Simmonds (Wales)
Munster v Bennetton Treviso (Irish Independent Park, Limerick – Kick-off: 15.05; 14.05 GMT)
Munster ‘s only defeat in their last seven Pro12 fixtures was 12-26 to Ospreys at Liberty Stadium in March. The Munstermen have won their last eight matches at Irish Independent Park since The Blues won there 17-6 in January 2013.
Munster have won all 14 previous home ties they have played against Italian opponents in all tournaments.
Benetton Treviso have slipped to four straight defeats in the Pro12 and failed to pick up a league point in that sequence, since beating Cardiff Blues at Stadio Monigo in February.
Treviso have not won a game outside of Italy since a trip to Scarlets in the last round of the 2012/13 Pro12 season.
The two sides have met on nine previous occasions in the Pro12 with Munster having the edge by six wins to three, with all three Treviso wins being in home matches.
Teams:
Munster: 15 Felix Jones, 14 Keith Earls, 13 Andrew Smith, 12 Rory Scannell, 11 Simon Zebo, 10 Ian Keatley, 9 Conor Murray, 8 CJ Stander, 7 Tommy O'Donnell, 6 Peter O'Mahony (captain), 5 Donnacha Ryan, 4 Billy Holland, 3 Stephen Archer, 2 Duncan Casey, 1 Dave Kilcoyne.
Replacements: 16 Eusebio Guinazu, 17 John Ryan, 18 BJ Botha, 19 Donncha O'Callaghan, 20 Dave O'Callaghan, 21 Duncan Williams, 22 JJ Hanrahan, 23 Ronan O'Mahony.
Benetton Treviso: 15 Jayden Hayward, 14 Andrea Pratichetti, 13 Luca Morisi, 12 Enrico Bacchin, 11 Ludovico Nitoglia, 10 Sam Christie, 9 Edoardo Gori, 8 Mat Luamanu, 7 Francesco Minto, 6 Paul Derbyshire, 5 Corniel Van Zyl (captain), 4 Marco Fuser, 3 Rupert Harden, 2 Davide Giazzon, 1 Matteo Zanusso.
Replacements: 16 Albert Anae, 17 Josè Novak, 18 Romulo Acosta, 19 Meyer Swanepoel, 20 Nicola Cattina, 21Marco Lazzaroni, 22 Simone Ragusi, 23 James Ambrosini.
Referee: Ben Whitehouse (Wales)
Assistant Referees: Dudley Phillips (Ireland), Brian MacNeice (Ireland)
TMO: Kevin Beggs (Ireland)
Newport Gwent Dragons v Scarlets (Millennium Stadium, Cardiff – Kick-off: 16.45; 15.45 GMT)
Newport Gwent Dragons have won their last three Pro12 fixtures but have not won four in a row in the competition for a decade. The Dragons have appeared just twice at Millennium Stadium, losing both "Judgement Day" encounters, to Scarlets in 2013 and to Ospreys last season.
Scarlets’ two defeats in the last six rounds of Pro12 matches came against Ulster in Belfast in Round 16 and at home to Edinburgh in Round 18.
Scarlets have made three previous trips to Millennium Stadium, beating Bath 27-26 in the semifinal of the Anglo-Welsh Cup in 2006, and then the last two "Judgement Days" – beating Dragons in 2013 and tripping up to The Blues twelve months ago.
Dragons only victory in their last 13 Pro12 encounters with Scarlets was 23-16 at Rodney Parade in September 2013.
Teams:
Dragons: 15 Geraint Rhys Jones, 14 Tom Prydie, 13 Tyler Morgan, 12 Jack Dixon, 11 Hallam Amos, 10 Dorian Jones, 9 Jonathan Evans, 8 Taulupe Faletau, 7 James Benjamin, 6 James Thomas, 5 Rynard Landman (captain), 4 Matthew Screech, 3 Brok Harris, 2 Rhys Buckley, 1 Phil Price.
Replacements: 16 T. Rhys Thomas, 17 Luke Garrett, 18 Lloyd Fairbrother, 19 Nick Crosswell, 20 Ollie Griffiths, 21 Luc Jones, 22 Carl Meyer, 23 Ashton Hewitt.
Scarlets: 15 Liam Williams, 14 Harry Robinson, 13 Hadleigh Parkes, 12 Scott Williams, 11 Steff Evans, 10 Rhys Priestland, 9 Aled Davies, 8 John Barclay, 7 James Davies, 6 Aaron Shingler, 5 Lewis Rawlins, 4 Jake Ball, 3 Peter Edwards, 2 Ken Owens (captain), 1 Phil John.
Replacements: 16 Ryan Elias, 17 Wyn Jones, 18 Jacobie Adriaanse, 19 Rob McCusker, 20 Rory Pitman, 21 Rhodri Williams, 22 Steven Shingler, 23 Regan King.
Referee: George Clancy (Ireland)
Assistant Referees: Neil Hennessy (Wales), Sean Brickell (Wales)
TMO: Tim Hayes (Wales)