Few saw this coming and even fewer predicted such a landslide as Wales overpowered and outsmarted their more experienced rivals for a place in the World Cup semi-finals.
Some 24 years after these teams met here in Wellington in their first ever World Cup fixture, Wales were again the victors though this time by a far more convincing margin.
That campaign in 1987 saw Wales achieve their only previous appearance in a semi-final before eventually finishing third. This time, under Warren Gatland, there are those believing they could go one further.
They will face France in Auckland in six days for a place in the final, and in this form Wales have every reason to believe that history is in the making.
Such was the convincing manner of the triumph that the only thing left in doubt was whether the winners would relax their self-imposed alcohol ban, just for one night, to celebrate a famous victory.
Wales have slipped under the radar here in New Zealand, more than happy for their opponents to be talked up as potential finalists. This game was billed as the last chance for Ireland's Golden Generation to go one step further than any of their predecessors in green at the World Cup and add another accolade after the country's many Heineken Cup triumphs and the 2009 Grand Slam.
The Irish were firm in the belief that their back-row trio would lead them to victory, but they had not counted on their determined and well-conditioned Welsh counterparts, led by Sam Warburton, who exposed Ireland's utter lack of a Plan B.
When they chopped down Sean O'Brien, Jamie Heaslip and Stephen Ferris at source, Ireland faltered and at times looked to have no clue where to go next. It made life easy for the well-drilled Welsh defence that engulfed every emerald shirt within sight.
Wales' defence had been heroic all through their pool matches and they were comfortable in soaking up raid after raid and waiting for what seemed the inevitable Irish mistake.
The spirit of the Welsh was characterised by the first-half effort of the lock Luke Charteris, who put in 19 tackles, carried strongly and won his share of line-out ball. He had played himself to a virtual standstill by the break when he was replaced by Bradley Davies after taking a blow to his shoulder. As well as the back-row battle, the wily Welsh front row put their much-vaunted Irish counterparts into clearer context. Adam Jones buckled Cian Healey, Gethin Jenkins never conceded an inch to Mike Ross and there was simply nowhere Ireland could gain an advantage.
Declan Kidney's selection of Ronan O'Gara to direct operations caused a bit of a stir and with first use of the typically strong Wellington wind he had a wretched opening 40 minutes. He left before the hour, but the introduction of the Leinster half-back pair of Eoin Reddan and Jonny Sexton came too late to change the pattern. In contrast, Gatland had put his faith in youth, choosing at full-back Leigh Halfpenny, who passed his test with flying colours, and Rhys Priestland at No 10 ahead of the 102-capped Stephen Jones. The young Scarlet responded with a commanding display.
Any fears that Wales would live to regret the penalties he struck against either post were soon dispelled. The team were unflappable in the face of a mass of green inside the Cake Tin that made Wellington feel more like a November evening in Dublin.
They possessed an unquenchable belief based on their fitness – fashioned in the bitter temperatures of a Polish cryotherapy centre during a summer training camp – and their ball-playing ability. It took the young bucks a mere three minutes to work the old master Shane Williams over in the right corner for his 58th Test try and the die was cast.
Jamie Roberts' power up the middle punched huge holes in the Irish defence and where he led, co-centre Jonathan Davies wasn't far behind. Davies got his rewards in the second half when he danced through some very poor tackling to bag his side's third try which had followed an exquisite finish by Mike Phillips to put Wales ahead again after Keith Earls had brought the Irish back to 10-10 with his try in the corner.
Phillips was named man of the match after arguably his finest performance in a Wales shirt. Wales now head to Auckland firmly on the French radar, but with renewed belief that this time they can go all the way.
Wales L Halfpenny; G North, J Davies, J Roberts, S Williams; R Priestland (J Hook, 77), M Phillips; G Jenkins, H Bennett, A Jones, L Charteris (B Davies, 40), A W Jones, D Lydiate, T Faletau, S Warburton (capt).
Ireland R Kearney; T Bowe, B O'Driscoll (capt), G D'Arcy, K Earls (A Trimble, 70); R O'Gara (J Sexton, 55), C Murray (E Reddan, 55); C Healy, R Best, M Ross, D O'Callaghan, P O'Connell, S Ferris (D Ryan, 18), J Heaslip, S O'Brien.
Referee Craig Joubert (South Africa)
Tries: Shane Williams, Phillips, J Davies
Cons: Priestland 2