It may not sound like a unique occasion, these great rivals have been playing each other for well over a century after all, but yesterday's meeting in Limerick was a little different. Leinster had not played in European rugby's most hostile environment since 1995 and for a generation of their players this fixture represented a first experience of a full Thomond Park, the venue that has helped create so many memorable Heineken Cup occasions.
For some 50 minutes it was nowhere near as uncomfortable as the visitors probably imagined it would be, as a passionate if one-dimensional game hung in the balance. But once Leinster lost their discipline at the breakdown, and Ronan O'Gara had punished them with five second-half penalties, the game changed rapidly.
The performance of the young fly-half Jonathan Sexton regressed from that of relative calm to something close to all-out panic as Munster began to exert their forward power and the substitute full-back Rob Kearney dropped the first two up-and-unders aimed in his direction and never fully recovered from the shock.
This is the kind of venue that can do that do you. The disappointing thing from a Leinster point of view was that it had all started rather brightly. Sexton showed great nerve after three minutes to dissect the posts with a penalty after Donncha O'Callaghan had infringed on the floor, but his kick only served to wake Munster from their post-Christmas slumber.
Three times in as many minutes their attempts to maul their way over from close range were halted illegally by Leinster hands and Alan Lewis lost patience. Keith Gleeson was sent to the sin-bin, Munster bundled Leinster over the line from the scrum and the referee signalled a penalty try as Jamie Heaslip prevented Denis Leamy from dotting the ball down.
If this try was grounded in sheer determination, Leinster's reply on 20 minutes was pure guile. A beautifully floated cut-out pass from Sexton on the Munster 22 found Denis Hickie floating across from the blindside wing and Girvan Dempsey ran a sweet line off him to split the Munster defence and stroll over.
Penalties exchanged by Sexton and O'Gara left Leinster with a one-point interval lead, but as Leinster's young guns got themselves in a muddle and their pack infringed at the breakdown with increasing frequency, three more unerring O'Gara penalties gave Munster an eight-point advantage heading into the final quarter.
From there, the European champions battered their neighbours around the fringes and turned them at every given opportunity with O'Gara's boot. The fly-half added two more penalties as the dusk and fog descended, and towards the end the visiting players looked as though they would have preferred to be anywhere else on earth, glad to wait another decade before returning - at the very least.
Munster Payne; Kelly, Murphy, Halstead, Dowling; O'Gara, Stringer; Pucciariello (Hurley, 64), Sheahan, Hayes, O'Callaghan, O'Connell (capt), O'Sullivan, Wallace, Leamy (Coughlan, 77)
Try Penalty. Con O'Gara. Pens O'Gara 6.
Sin-bin Sheahan, 40.
Leinster Dempsey (Kearney, 48); Horgan, O'Driscoll (capt), D'Arcy, Hickie; Sexton (Contepomi, 67), Easterby (Whitaker, 64); McCormack, Jackman, Wright (Pala'amo, 67), Hogan, O'Kelly (Finegan, 61), Keogh (Jowitt, 59), Gleeson, Heaslip.
Try Dempsey. Pens Sexton 2.
Sin-bin Gleeson, 11.
Referee A Lewis (Ireland). Attendance 13,200.
