Just after 5.0 on Saturday, the balance of power in Irish rugby that had been moving inexorably eastward since September took a seismic shift when European champions Toulouse ceded their title to Leinster.
It was a magnificent match -- more worthy of a final -- between the two best teams in the competition. Indeed, it probably would have been the final but for the French team's inexplicable loss in January to Wasps in their last pool game.
Toulouse were absolutely true to their traditions and played magnificent continuity rugby in perfect conditions. They were marginally the better side, but lost out against immovable defence and unquenchable self-belief.
Leinster never succeeded in using Isa Nacewa as a counter- attacking force, nor did they get the ball wide with any regularity, yet they won because they simply never gave up.
This team now joins snooker player Cliff Thorburn and golfer Nick Faldo among the great 'grinders' of sport.
A couple of hours earlier, Munster had lost at Thomond Park to run-of-the-mill English Premiership side Harlequins, and were lucky not to be humiliated.
It was indicative of the team's problems that, when the match was slipping away, the players brought on to attempt to right the ship were John Hayes, Marcus Horan and Peter Stringer, heroes all of a bygone age.
The gulf between Ireland's two major rugby teams is encapsulated in the flow of young talent in Leinster.
In the Aviva, waves of Toulouse attacks perished on the rock of Jamie Heaslip, Sean O'Brien and Kevin McLaughlin, while in Limerick, James Coughlan, David Wallace and Denis Leamy were overpowered.
At centre, Munster were reduced to poor passers like Sam Tuitupou and Lifeimi Mafi. Recruits from the Pacific Islands are cheap as the English Premiership clubs have discovered, but they rely on the physical rather than the sublime to open defences.
When Felix Jones butchered the pass to put Doug Howlett over, you sensed that Nacewa or a half dozen of Joe Schmidt's other backs would have given the Kiwi a legitimate pass.
All was not sweetness and light at the Aviva, as Luke Fitzgerald continues his battle with form. The young man was not tested with kicks, but after 50 minutes he made a fine catch only to meander infield without pace or intent before finally giving the ball to a worse-placed Nathan Hines.
Fitzgerald will come through this hiatus and we can but hope that it will not be without major cost to player or team.
At scrum-half, too, there was a problem for Schmidt, where Eoin Reddan kicked badly and, like every scrum-half in Ireland bar Stringer, takes a step or more when passing.
The rule is simple: run to hold the defenders if passing to support; pass in one movement if the backs want it wide. Isaac Boss, Tomas O'Leary and Conor Murray please copy.
The pre-match doubts about young French No 9 Jean-Marc Doussain were unfounded as he dominated his opponent and put him on his back side in the build-up to the second Toulouse try from Louis Picamoles.
Interestingly, Toulouse made consistent in-roads off the back of the scrum using the '8 to 9' move.
This is a tactic that has fallen into disuse in Irish rugby, no doubt predicated by the dreadful scrummaging of the last decade. Leinster now have the platform, the dynamism at 8 and the pace at 9 to rival the French and ought to consider the option.
Two foreign players leave their respective provinces at season end with what could be serious damage to the future prospects of the teams.
Paul Warwick leaves a huge hole in Munster's attacking cupboard and less obvious, but equally important, Nathan Hines departure from Leinster will soften the hard edge which was so crucial on Saturday.
The Scottish international was magnificent and his physicality was just what was wanted when playing against a French pack in full cry. A similar performance will almost certainly be required in the final.
The game at the Aviva was a great occasion for Irish sport. Leinster have now delivered three full-houses in the stadium; a task that national team may find beyond them in 2012. The atmosphere is great, the feel-good factor important for an economically battered population and the sponsors are ecstatic.
But the game needs money to survive let alone expand. Leinster chief executive Michael Dawson will like his colleagues across Europe be searching the globe for players to strengthen his squad.
The salary cap in England means that Leinster can outbid Leicester, Harlequins, et al. To continue to do so, full houses at the Aviva and the RDS are vital. Munster may find it more difficult if the team does not win.
The quality of the players recruited is vital. For every Hines and Warwick there have been signings like Peter Borlase at Munster and Clint Newland at Leinster, who would struggle at club level in Ireland.
The Southern Hemisphere has mediocre players like anywhere else, Irish rugby does not have to provide a retirement fund.
Saturday was a day of mixed emotions as once-mighty Munster were humbled and the one-time pretenders at Leinster demonstrated their fitness for greatness.
The future looks bright, but there could be a cold front moving in from the Atlantic coast.