In the intense Dublin cauldron, before a sell out crowd at the Aviva Stadium, this absorbing test match was everything it was billed to be; brutal trench warfare with overly officious refereeing.
On that big stage Ireland rose for the challenge and thoroughly deserved their victory – their third in 33 attempts against the All Blacks after the breakthrough 2016 and '18 triumphs - having largely controlled the contest and forcing the All Blacks to make a staggering 238 tackles.
In their last six tests over the past five years the All Blacks and Ireland have now won three each – Ireland claiming the last two ties in Dublin to underline the difficulties of prevailing there.
Defeat puts the All Blacks' season into immediate context with their second loss, the first against the Springboks, revealing familiar flaws for Ian Foster's men, particularly up front where they were again second in the physicality stakes.
Ireland's dominance forced the All Blacks live off scraps, reducing the visitors to 39 per cent possession and 33 per cent territory.
With France in Paris to come next week these two tests were always going to provide insight as to where this All Blacks team sits at present. They, clearly, have significant work to do.
Under Andy Farrell Ireland have now notched seven victories in a row which includes knocking over England, Japan, Scotland and the All Blacks.
Ireland played much more rugby than previous in years and ultimately gained the rewards for doing so. The Jonathan Sexton wrap around remains a favoured pet play but with their dominance of possession, Ireland regularly chased width and often offloaded in contact.
The All Blacks, conversely, kicked away the vast majority of their limited ball. With the pack outmuscled and the backline battling to deal with the inevitable rush defence, the All Blacks were guilty of misfiring passes that went behind the man and making errors in contact.
The All Blacks managed a couple of moments of brilliance but they struggled to build any consistent pressure through phases, and when they review the tape it will show they were beaten in the collisions.
They had no right to but the All Blacks led 10-5 at halftime despite spending almost the entire first half on the backfoot defending their own line.
Straight after the break, though, Ireland swung the match with two tries to Ronan Kelleher and Caelan Doris, the second symptomatic of a hugely fatigue defensive line.
Trailing 20-10 with 14 minutes remaining the All Blacks, with their backs to the wall, summoned the energy to counter punch. From inside their own 22 David Havili set Will Jordan away with a skip ball to the edge and after a brilliant chip, regather and offload exchange Rieko Ioane put the Crusaders finisher in.
Akira Ioane, after replacing Ethan Blackadder, had his try overturned with 12 minutes remaining after the TMO ruled he received a forward short ball from brother Rieko.
All Blacks captain Sam Whitelock, somewhat surprisingly, opted to take the take shot with 11 minutes left, edging his men to 23-20, only for New Zealand-born playmaker Joey Carbery to kick Ireland clear with three penalties down the stretch.
Despite being under the pump the All Blacks opted not to inject replacement lock Tupou Vaa'i or halfback Finlay Christie into the contest.
The All Blacks were on the backfoot from the outset when Codie Taylor copped an early yellow card for a late shot on Sexton. The TMO was determined to hand Taylor a spell on the sidelines, showing countless replays in attempting to influence referee Luke Pearce.
Taylor's arm made a glancing connection with Sexton's head – enough for Pearce to brandish the yellow.
The All Blacks were forced to absorb relentless pressure. Camped on their own line for extended periods as wave after wave of Ireland attack battered away, somehow the All Blacks held firm.
Making 158 tackles in the first half alone it was nothing short of heroic defence; Ireland leaving points on the park after turning down three shots at goal. Later in the match though, those tackles bit into the All Blacks' resolve.
Former Chiefs and New Zealand Māori outside back James Lowe was a prominent threat throughout and he finished Ireland's sole first half try in the corner. Ireland were denied a second strike to Tadhg Furlong after hooker Kelleher crawled on the deck.
Such was their lack of possession, the All Blacks had only two genuine scoring chances in the first half. They clinically took one. The first came from a perfectly-executed set move with Beauden Barrett finding Will Jordan through a pin-point cross-field kick on the edge.
Garry Ringrose and Andrew Conway stopped a charging Jordie Barrett but, from the ruck, Anton Lienert-Brown lost the ball with Ireland fortunate to not be called offside.
The All Blacks lost two key pieces of their backline in the first half as Beauden Barrett failed his HIA after 21 minutes and Lienert-Brown departing two minutes before the break, forcing a reshuffle with Richie Mo'unga and David Havili coming off the bench.
When Ioane's try was ruled out hopes of another great escape faded as composure deserted the All Blacks and Ireland turned the screws.
It was that sort of night for the All Blacks where they struggled to gain dominance and impose their game. The concerning nature of defeat will, therefore, sting just as much as the result.
All Blacks: Codie Taylor, Will Jordan tries, Jordie Barrett pen 2, con 2
Ireland: James Lowe, Ronan Kelleher, Caelan Doris tries, Jonathan Sexton con, pen, Joey Carbery pen 3
HT: 5-10
