It will be first plays fourth in the Magners League on Sunday but there will be more than just league points on the line at the RDS for the players, management teams and what is expected to be an 18,500-capacity crowd.
MAGNERS LEAGUE: Sunday, September 28
LEINSTER v MUNSTER, The RDS, 7pm (live Setanta Sports 1)
Team News: The Leinster team to face Munster in Sunday's sell-out Magners League clash at the RDS has been named.
Summer signings CJ Van Der Linde and Rocky Elsom will both make their debuts for Leinster in Sunday's interprovincial derby.
Skipper Leo Cullen partners Malcolm O'Kelly in the second row with Elsom lining up in the back row alongside Shane Jennings and Jamie Heaslip.
In the back-line, Chris Whitaker partners Jonathan Sexton at half-back with Shane Horgan starting on the right wing, Luke Fitzgerald on the left and Girvan Dempsey at full-back.
Meanwhile, Munster coach Tony McGahan has made five change to the team that started last week's win over Cardiff for this Sunday's showdown with Leinster.
Keith Earls takes over from Denis Hurley at full-back with the other change in the back-line seeing Tomas O'Leary preferred from the off to Peter Stringer, who is named on the replacements bench.
In the front row, Marcus Horan returns at loosehead prop in place of Tony Buckley.
Meanwhile, Donncha O'Callaghan will partner the team captain Paul O'Connell in the second row.
And the experienced David Wallace takes the number 7 jersey from Niall Ronan, whose two tries last weekend helped Munster to a bonus point win.
LEINSTER: Girvan Dempsey; Shane Horgan, Brian O'Driscoll, Felipe Contepomi, Luke Fitzgerald; Jonathan Sexton, Chris Whitaker; Ronan McCormack, Bernard Jackman, CJ Van Der Linde, Leo Cullen (capt), Malcolm O'Kelly, Rocky Elsom, Shane Jennings, Jamie Heaslip.
Replacements: Stan Wright, John Fogarty, Trevor Hogan, Cameron Jowitt, Sean O'Brien, Chris Keane, Rob Kearney.
MUNSTER: Keith Earls; Doug Howlett, Rua Tipoki, Lifeimi Mafi, Ian Dowling; Ronan O'Gara, Tomas O'Leary; Marcus Horan, Jerry Flannery, John Hayes, Paul O'Connell (capt), Donncha O'Callaghan, Donnacha Ryan, David Wallace, Justin Melck.
Replacements: Frankie Sheahan, Federico Pucciariello, John O'Sullivan, Alan Quinlan, Peter Stringer, Paul Warwick, Barry Murphy.
Referee: Simon McDowell (Ireland) Assistant Referees: Colin Stanley, David Wilkinson (both Ireland) Television Match Official: Marshall Kilgore (Ireland)
Say What: Michael Cheika (Leinster) - "Munster have looked very good. They have definitely benefited from having all their player available from day one and they've returned 14 from 15 points so that pretty much says it all really.
"I think that they're an improving team. They have a lot more clarity about how they want to play their wide game and they do it well because they have some great finishers.
"(Doug) Howlett has really been in excellent form, trailing behind the back and in his work off the ball. I think that their coach (Tony McGahan) has been very clever in the way he has used his squad.
"He has given himself a really good choice to select from, so I've been pretty impressed by what he has done so far.
"It's always good to get your full squad together. We have close to a full deck to choose from in the forwards. It's slightly different in the backs (with Isa Nacewa and Gordon D'Arcy injured).
"Rocky (Elsom) has had an interrupted Tri Nations because he had one week off with an injury, but there seems to be quite big gaps in this format where teams played three games and then had a break.
"CJ (Van Der Linde) has obviously had a bit of a break, so he should be fresh!"
Tony McGahan (Munster) - "I don't think it's right to say we got beaten up (by them in April), but we just didn't turn up and give ourselves a chance to do enough.
"Leinster played with a lot of intensity that night. Now we're going to focus on ourselves and what we can bring to the table.
"That's how we've approached the season so far and that's what we intend to do on Sunday.
"(But) from a coaching perspective I don't think we're near where we should be at the minute. We've had some pace on the work we've done and that has been pleasing, I suppose. But we still feel we have a little bit to go.
"I think we need to get more from our kicking accuracy, we are still conceding penalties on our own attack ball and have to be more accurate.
"But some of it is more a referee's interpretation than anything, and that we need to adjust to."
Top Scorers:2008/09 Magners League - Points: Leinster: Felipe Contepomi 41; Munster: Paul Warwick 25; Tries: Leinster: Luke Fitzgerald 4; Munster: Keith Earls 4.
RECENT LEAGUE MEETINGS:
Sunday, October 9, 2005 - Munster 33 Leinster 9, Musgrave Park Saturday, December 31, 2005 - Leinster 35 Munster 23, The RDS Friday, October 6, 2006 - Leinster 27 Munster 20, Lansdowne Road Wednesday, December 27, 2006 - Munster 25 Leinster 11, Thomond Park Friday, November 30, 2007 - Munster 3 Leinster 10, Musgrave Park Saturday, April 12, 2008 - Leinster 21 Munster 12, The RDS
- Defending Magners League champions Leinster have been defeated just once since they moved to the RDS at the start of last season - they lost 52-23 to the Scarlets there on October 5, 2007
- Leinster are unbeaten in their last eight encounters against their fellow Irish teams. Their last home defeat in the league to an Irish province was a 15-8 reversal against Munster at Donnybrook on September 5, 2003
- Munster's 28-20 win over the Cardiff Blues last Saturday sees them sit atop the Magners League table for the first time since February 2006
- Munster's last win in Dublin was 'that' 30-6 success over Leinster in the semi-final of the European Cup at Lansdowne Road on April 23, 2006
- Leinster have won three of their last four encounters with Munster, including a season's double last term