Triumphant Ireland fought magnificently through an exhausting war of attrition to score a breath-taking win over champions Wales 73,320 emotional fans in the Millennium Stadium.
A memorable contest provided extravagant entertainment as Wales recovered after Ireland's blistering start to ensure a hugely competitive second half. In the process, Ireland were obliged to demonstrate just how highly developed their all-round game is when they strike form.
First half, we were treated to a stunning exhibition of slick, attacking rugby from a dominant Ireland; second half, Ireland's rock-hard defensive qualities were tested to the full as Wales finally found inspiration.
Ireland showed more initiative and ambition behind the scrum, with the half-backs Conor Murray and Jonathan Sexton linking effectively and mixing their use of possession cleverly.
Sexton was 100pc successful from the tee and the extra points he contributed were crucial as Ireland were later obliged to defend their lead.
And with Brian O'Driscoll and Simon Zebo, especially, in flamboyant mood it was a surprise that when the final whistles shrilled Wales had matched them for tries scored. The eight-point differential at the climax was not reflective of just how well Ireland had played in a brilliant first half.
It was no surprise that Wales mounted a spirited revival after turning over a whopping 20 points in arrears. But Ireland, critically, had stretched their lead by another seven points and were still in control until Alex Cuthbert's 50th-minute try sparked Wales' vigorous charge.
Wales contributed handsomely to the overall excitement by testing Ireland to the core for the last 30 minutes. Their recovery magnificently enhanced the drama of the occasion and heightened the excitement as Ireland showed how well-organised and committed they are in defence.
"I can't remember a game when everyone has come off and the tanks are just empty," said captain Jamie Heaslip.
"Everyone is just shattered. The effort out there was just colossal. At times it felt like Wales were going through 50 phases of possession when in reality is was probably only something like nine. It really was that intense. Those last 20 minutes were brutal."
Playing such talented opposition in Cardiff in the first match was going to either kill or cure Ireland's championship so it must have been a tense occasion for those involved. The final result was spectacular for Ireland.
It was also vindication for Declan Kidney and endorsement of his selections. The game plan worked to perfection and a well-balanced selection did the business in attack and defence.
The make-up of his back-row was particularly hotly debated. All three were outstanding. And while there are definitely some areas where Ireland will need to improve ahead of the England game on Sunday, this was a massive fillip for the coaching staff.
True to form, the coach wasn't getting carried away.
"We've had our bad days and we've had to take those on the chin but we'll just take today as one of the good days, but because of the nature of the competition we'll enjoy it for half an hour and then get on for the next one eight days later," said the head coach.
Ireland will need every one of those eight days to recover from Saturday's exertions.
At this juncture Gordon D'Arcy's leg injury – "he took a heavy bang to the knee" – is the biggest concern, although Peter O'Mahony was also forced from the field after sustaining "a couple" of blows to the head and Mike Ross also looked a little groggy when he departed in the 68th minute.
The flanker will be assessed through the week but, happily, isn't a doubt for the England game. Novenas will be sent up for Ross' well-being this week.
Ireland were in irresistible form from the start. The manner in which they almost nonchalantly broke down the pitch to drive Wales into their own '22' inside the opening few minutes suggested that the home side had a battle on their hands.
The early signs did not lie but they gave no clue as to how vigorously and successfully Ireland would take to the challenge and how enthusiastically they would engage in the battle.
It was also wholly fitting that the spark to ignite Ireland was presented in the guises of O'Driscoll and Zebo, the master and the willing pupil if you will. O'Driscoll provided the genius with his dart and cut-out pass that took both Jonathan Davies and Leigh Halfpenny out of the game.
How O'Driscoll managed to get the ball away and into Zebo's hands with a forest of red jerseys crowded around him remains one of the wonders that is O'Driscoll's brain. It was genius at work and any attempt to make sense of that genius would simply devalue the memory of the pass.
The bandage he sported on his head for much of the game made him seem all the more heroic and his performance gave us a timely reminder of how fortunate we are to have such a player of skill, surging athleticism, bravery and competitive enthusiasm.
It is only when he's gone we will realise just how good he was. Is it any wonder Kidney is steadfastly refusing to believe this will be his last Six Nations championship?
"Brian is everything that you write about him," agreed Kidney. "He's one of the few fellas who lives up to the adjectives you say about a player."
Zebo's part in the melodrama was no less spectacular. Moments before touching down, the winger had been chatting with the linesman like a man without a care in the world. Zebo doesn't do nerves.
"No, I won't give you any adjectives about that fella," laughed Kidney afterwards. The message was clear: Zebo is not a player who needs confidence fed to him by his coach.
His outrageous heel-flick when at full tilt to rescue and bring the ball under control in the lead-up to Cian Healy's try was spectacular.
It was a reminder that, in a sport where, increasingly, coaches believe 'bigger-is-better', there will always be a place for instinctive genius – even in an increasingly gladiatorial contest.
Neither is there need to be overly critical of Ireland's defence. Of course, they should have done better for Cuthbert's try. Keith Earls, in particular, was caught out of position. But two of the tries were conceded when they were down to 14 men.
And Ireland were, for the most part, implacable in face of mounting Wales challenges.
They frustrated the Welsh on a number of occasions and put in a colossal number of tackles. Sean O'Brien's tackle-count alone was 23.
"It was colossal," added Kidney. "You can only coach so much. It's only if they want to do it that they will do some of the stuff they did there.
"Systems will get so many things in place, but if there was a hole to be plugged, whoever popped his head up said 'I'll get in there and plug that hole'.
"The willingness of fellas to do that is just colossal, and hopefully the reward for it is when they wake up in the morning and they are sore, but they will feel, 'Yeah, I'm sore alright but it was worth it'."
When they review the match Ireland will see so much to be happy with. They were excellent out of touch – except for one poor throw from Rory Best – the scrum was solid and they have started the competition with a hugely important win.
England are next up and they will, as Kidney said, provide a different kind of test. But Ireland will face into that particular examination with confidence. These young lads don't know fear and the older fellas are feeding off that enthusiasm.
Whisper it for fear that shouting from the rooftops could be a fatal jinx ... but this could be a memorable season.
Wales – L Halfpenny; A Cuthbert, J Davies, J Roberts, G North; D Biggar (J Hook 74), M Phillips (L Williams 64); G Jenkins (P James 66), M Rees (K Owens 52), A Jones (C Mitchell 73); A Coombs, I Evans (O Kohn 74); A Shingler (J Tipuric 45), S Warburton, T Faletau.
Ireland – R Kearney; C Gilroy, B O'Driscoll, G D'Arcy (K Earls 45), S Zebo (E Reddan 80); J Sexton, C Murray; C Healy, R Best, M Ross (D Fitzpatrick 69); M McCarthy (D O'Callaghan 74), D Ryan; P O'Mahony (C Henry 52), S O'Brien, J Heaslip.
Ref – R Poite (France)