Gloucester's fate in January 2003, when Munster had to beat them by four tries and 27 points to qualify for the knock-out stages, set the miraculous bar at Thomond Park ludicrously high.
The winning drop goal, which Ronan O'Gara conjured with the last kick four minutes after the hooter, against Northampton three seasons ago pushed it higher still.
Munster had, of course, worked other victories bordering on the miraculous down the years but nothing of late, at least not before the annual Dublin trip on GUINNESS PRO12 business.
Home defeats by Edinburgh and the Ospreys hardly renewed their entry into the Magic Circle and wasn't it also a fact of life that Munster hadn't won in the capital for six years?
They were underdogs for sure, just as they had been going into the European Cup final in April 2006 against the same opposition at what used to be the same venue, Lansdowne Road.
Munster were over the hill and far away long before the end on a day when the magnitude of their victory, 30-6, signalled that their old rivals had been torn to shreds.
Of all those who spoke during the build-up, nobody proved quite as prophetic as Rob Kearney. "They always come out when they've been put down," Ireland's full back said of Munster only to be forced into a last-minute withdrawal after injuring himself in the warm-up.
Less than two hours later, Leinster would fall victim to a sort of miracle which not even Munster could have dreamt up. You play the champions on their grand stage, you lose four men to the bin in the second half and you end up winning? By a double-figure margin?
When Munster won that all-Irish semi-final en route to conquering Europe for the first time, they did so without falling foul of the referee to any damaging extent.
The only yellow card back then, to their Argentinian prop 'Freddy' Pucciariello, came far too late to have any affect on the outcome.
This time Munster were sent to the bin mob-handed which, if nothing else, guaranteed a record-breaking element to their success. No team in the PRO12 had ever had to take so many yellows on the chin in such a short space of time.
Damien Varley, BJ Botha, Dave Foley and Conor Murray traipsed off at various stages, ensuring that Munster twice found themselves down to 13 men. Leinster, 28-9 behind at one stage, had been cut too far adrift to have had any realistic hope of saving themselves.
After a trying start to his reign, Munster head coach Anthony Foley could scarcely have asked for more, other than to have kept all his troops on the field all the time. That they had negotiated the first four fixtures without a single binning against their name made it all the more surprising.
In the course of putting their season back on an even keel, Munster reminded everyone that their sense of occasion is as acute as ever. A day when almost 44,000 at the Aviva Stadium added up to the biggest single-match attendance in Europe hitherto this season confirmed their enduring penchant for the unexpected.
In the course of defending their title last season, Leinster lost just four matches, all away - to the Warriors in Glasgow (6-12), Munster in Limerick (15-19), Edinburgh at Murrayfield (6-11) and the Ospreys in Swansea (19-25).
This season they have already been beaten three times, by Glasgow (20-22), Connacht (9-10) and now Munster, the holders' first PRO12 defeat in Dublin since Ulster at the RDS in March 2013.
Meanwhile at the top, the Warriors and Ospreys continue to set the pace, each preserving their flying start with wins in Italy. Six tries at Treviso ensured the Glaswegians the bonus-point win which squeezed them back above the Ospreys with 23 points from a maximum 25.
Their Welsh rivals edged past Zebre in Parma, no mean feat given that Ulster had come to grief there the previous week. After toughing it out at Thomond Park six days later, Ospreys found themselves confronted with an even tougher challenge - winning without Dan Biggar.
With the Wales fly-half an early casualty, 20-year-old Sam Davies stepped into the breach and kicked the winning goals, all five of them. After a hat-trick of away wins, the Ospreys will be back amid familiar surroundings in Swansea for Sunday's Welsh derby against the Blues.
The Warriors - averaging fractionally more than four tries a game - are in Belfast on Saturday for what promises to be the GUINNESS PRO12 match of the weekend, against Ulster. Gregor Townsend's team know what it takes to win there, James Eddie's only try of the match having done the trick for them 13 months ago.
Elsewhere Munster will demand a return to winning ways at home to the Scarlets on Friday night without needing to invoke another miracle while Leinster, ravaged by injury, head for Zebre with previous little margin for further error.
For the record: April 23, 2006 - European Cup semi-final at Lansdowne Road
Leinster 6 Munster 30
Leinster: G Dempsey; S Horgan, B O'Driscoll, capt, G D'Arcy, D Hickie; F Contepomi, G Easterby; R Corrigan (S McCormack, 68th min), B Blaney, W Green; B Williams, M O'Kelly; C Jowitt (E Miller, 56th min), K Gleeson, J Heaslip
Penalties - Contepomi 2
Munster: S Payne; A Horgan, J Kelly (R Henderson, 12th min), T Halstead, I Dowling; R O'Gara, P Stringer; F Pucciarriello, J Flannery, J Hayes; D O'Callaghan, P O'Connell; D Leamy, D Wallace, A Foley, capt (K Roche, 73rd min)
Tries - Leamy, O'Gara, Halstead; Cons - O'Gara 3; Pens - O'Gara 3
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