The Celtic nations will have their moment in the spotlight when the Pro12 play-offs get underway on Friday - with Ospreys hosting Munster and defending champions Leinster hosting the Glasgow Warriors a day later.
Warriors head coach Sean Lineen has challenged his players to take their game to the next level at the RDS.
The play-off match will see the Warriors seek to become only the second team to defeat the reigning European champions twice this season, Glasgow having recorded a 23-19 success in the first Pro12 meeting between the teams in Ireland last September.
Leinster have since lost just once in all competitions, with the Warriors one of only two teams to take points off them in the Pro12 this calendar year, courtesy of a 10-10 draw at Firhill back in February.
The Dubliners underlined their class in the Heineken Cup head-to-heads, inflicting a 38-13 defeat on the Warriors at the RDS before edging a tighter affair 23-16 in Glasgow.
Lineen believes it will take "something truly special from all 23 players" to see off a team who have booked another Heineken Cup final date for the following week, but has emphasised the belief underpinning his squad's approach.
"We've shown great consistency and character to reach the semifinals, but this is where the hard work really begins," the Warriors coach said.
"We're not satisfied just to be in the play-offs; we're absolutely determined to keep our run going, and that means finding a way to beat a side who are the benchmark for every other team in Europe.
"Leinster's record in both the Pro12 and Heineken Cup these past few years speaks for itself, and you only need to look at the statistics to see how hard it is to beat them.
"But we have confidence in ourselves, our game plan and each other and while we have huge respect for Leinster, we won't be standing back and admiring them.
"To win, we need every player to be better than they've ever been before. That's a big ask, but it's what it will take, and we've every confidence the players will deliver. They've risen to every challenge we've put in front of them this season, and this is undoubtedly the biggest yet."
* In the event of a tie at full time in a Pro12 semifinal or the Pro12 Final then extra-time will be played, consisting of two periods, each of ten minutes. If the score is still tied after extra-time, the Team that has scored the most tries in the match will be deemed the winner.
If the Teams are still tied on points and tries at the end of extra time then the winner will be determined by a place-kick competition. In the event that a place-kick competition is required, each team will nominate three goal-kickers who will take six place kicks between them from different positions along the 22-metre and 10-metre lines. The Team with the most place kicks scored will be the winner.
If the Teams are tied at the end of their six kicks, then sudden death will apply.
Only players in the playing area at the final whistle of extra-time may be nominated for the place-kick competition. No substituted players or players who have been shown a red card may take part at any time including any player who has received a yellow card and who remains in the sin bin at the time of the final whistle of extra-time.
We look at the semifinals!
Friday, May 11:
OSPREYS v MUNSTER
(Liberty Stadium, 19.35)
Ospreys and Munster have both reached the play-offs for a third successive year, with Ospreys going on to become champions in 2010 and the Munster last season.
Ospreys have won their last five Pro12 encounters and have been defeated just once at Liberty Stadium in the tournament this season: in round 17 to Glasgow. Ospreys only loss to an Irish province this season was 14-15 to Ulster at Ravenhill on 24 February.
Munster are unbeaten in their last three games, and have lost only once on the road in any competition in 2012: 17-21 at Aironi in round 14 of the Pro12. The Munstermen are unbeaten in their last five encounters with Welsh regions in all competitions.
The two sides met at this same stage last season, where Munster won 18-11 at Thomond Park. The Munstermen have won twice before at Liberty Stadium: 25-21 in January 2009 and 22-20 in April 2011.
Ospreys: 15 Richard Fussell, 14 Hanno Dirksen, 13 Andrew Bishop, 12 Ashley Beck, 11 Shane Williams, 10 Dan Biggar, 9 Kahn Fotuali'i, 8 Joe Bearman, 7 Justin Tipuric, 6 Ryan Jones, 5 Ian Evans, 4 Alun-Wyn Jones, 3 Adam Jones, 2 Richard Hibbard, 1 Paul James.
Replacements: 16 Scott Baldwin, 17 Ryan Bevington, 18 Aaron Jarvis, 19 James King, 20 Tom Smith, 21 Rhys Webb, 22 Matthew Morgan, 23 Tom Isaacs.
Munster: 15 Felix Jones, 14 Johne Murphy, 13 Keith Earls, 12 Lifeimi Mafi, 11 Simon Zebo, 10 Ian Keatley, 9 Conor Murray, 8 Peter O'Mahony, 7 Tommy O'Donnell, 6 Donnacha Ryan, 5 Mick O'Driscoll, 4 Donncha O'Callaghan, 3 BJ Botha, 2 Mike Sherry, 1 Wian du Preez.
Replacements: 16 Denis Fogarty, 17 Dave Kilcoyne, 18 Stephen Archer, 19 Dave O'Callaghan, 20 Paddy Butler, 21 Tomas O'Leary, 22 Ronan O'Gara, 23 Ian Dineen.
Referee: Alain Rolland (Ireland)
Assistant referees: Nigel Owens (Wales),Marius Mitrea (France)
TMO: Nigel Whitehouse (Wales)
Saturday, May 12:
LEINSTER v GLASGOW WARRIORS
(RDS Dublin, 19.35)
Leinster are still bidding to become the first side to achieve a European and Domestic double in the same season since Wasps in 2004. The Leinstermen have now reached the play-offs for a third successive season but have not won the title since 2008.
Glasgow Warriors are one of just two teams to have defeated Leinster in any competition since early September, doing so 23-19 at the RDS on 17 September. The Warriors have taken six of the 20 league points Leinster have conceded this season. The Scotsmen reached this stage in 2010 but lost out to Ospreys.
Glasgow have won just one of their seven previous visits to the RDS, and have won just once in Ireland since December 2009.
Glasgow Warriors: TBC
Referee: George Clancy (Ireland)
Assistant referees: John Lacey, Leo Colgan (both Ireland)
TMO: Marshall Kilgore (Ireland)
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Gilbert Blitz 8S rugby cleat is a great cleat at a great price of $69.99. Get a new pair of cleats today.
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
The All Blacks Performance t-shirt is black with hints of blue from the training jersey. Very Cool.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.