Additionally, since the inception of the Celtic League in the 2001–02 season, Leinster hold a 37–18 advantage in overall wins, with one draw in that time.
The fierce rivalry has grown since the turn of professionalism as both teams battled for domestic and European dominance, and has sometimes become a heated and bitter affair, on and off the pitch.
[2] The rivalry is heightened by the fact that Leinster and Munster have been among the stronger provinces in Irish rugby, and among the strongest teams in European competition.
[3] The birth of the modern era rivalry could be attributed to the Heineken Cup semi-final in 2006, when Munster defeated Leinster 30–6 in Lansdowne Road en route to winning their first European Championship.
A shift in fortunes occurred in 2009 however, when Leinster defeated Munster 25–6 at the same stage of the competition in front of 82,208 spectators at Croke Park, which was a world record attendance for a club game;[4][5] Leinster went on in 2009 to claim the first of four European titles to Munster's two.