Once bitten, the wounded All Blacks won't be shy to restore world order
From invincible to vulnerable? Well, perhaps. The all-conquering All Blacks' record-breaking international run was ceded in Chicago and today they find themselves in chilly Dublin where, perhaps, a winter of discontent may beckon.
A second successive defeat to a side to whom they had never succumbed in 111 years of international engagement would, to a side and a country back-boned by their exalted status in the sport, be viewed as verging on humiliation. Defeat would only be viewed through their prism and not reflect the massive strides which would have been taken by Joe Schmidt's Ireland; rugby in New Zealand is intensely parochial.
To many in the land of the long white cloud, the second best side in world rugby has always been New Zealand's XV; it is not long ago - eleven years - since their second string humbled Ireland in Dublin.
Hence, another defeat today to a side they have rarely rated would, amongst the folks back home at least, be seen as an embarrassment.
"You're scared to read the papers and head home," says Ireland assistant coach Greg Feek, a Kiwi in exile amongst the opposition.
"It was a bit like that. I remember getting home after the 1999 Rugby World Cup, and a couple of guys said 'what you coming back here so early?' because we'd failed.
"There are moments like that where you realise the weight that's on you in terms of the expectations.
"It's taken a few years, but I think this group of players, particularly in the last few years, have kind of embraced that pressure.
"Rather than dwell on it, and let it weigh them down, they seem to have got a game they can get excited about, which keeps the motivation going."
The All Blacks, befitting their status as the world's pre-eminent outfit, rarely make the same mistake twice and, as Schmidt astutely averred when referring to their error-ridden Chicago effort, their players also rarely make the same mistakes twice. Only three times since the sport went open in 1995 have they lost to the same country on successive occasions in the same season.
And two of those three occasions occurred in 1998, against Australia (who won three on the spin) and South Africa, during a campaign most keen observers reckon was the country's professional nadir.
The last time somebody managed back-to-back wins was in 2009 when the greatest Springbok team of the professional era - reigning Rugby World Cup champions and that summer's Lions conquerors - also achieved three successive wins.
In the entire history of the game, the feat has only been achieved 11 times and by four different teams. France (1994), Australia (1992) and South Africa (1970 & 1976) did it.
If 1998 was a professional nadir, there are a dwindling few who will cry into their Steinlager at the remembrance of 1949.
That season, South Africa managed to string together a barely credible four wins on the trot against their fierce rivals, to pour vinegar into wounds salted by that year's Aussie double.
Australia were the first country to puncture the aura, in 1929. Now Ireland, 88 years on, can become the latest but they will not be the first Irishmen to conquer this sporting Everest.
For the 11th team to complete this double against the men in black were, of course, the most distinguished and seminal Lions outfit of them all.
Fergus Slattery, Willie John McBride and Sean Lynch played in that four-match series, won 2-1 by the Lions.
Ireland have their own accumulated weight of history to overcome if they are to become history boys again, of course.
This is the 30th staging of the fixture, though only just under half of them happened during the first 80-year, amateur era of what had been only an occasional rivalry.
In recent times, history has shown that New Zealand thrive after a close game against Ireland; in 2002 and 2012, for example when Ireland let in 100 points in two games.
Now, another complete set of Irishmen stand on the verge of more history. They will be warned; to paraphrase another side's historic mantra, you never beat them twice. Well, perhaps. But rarely.