Richie McCaw was sin-binned and they even went down to 13 at one point but New Zealand held their nerve to come from behind and beat Argentina 26-16 at Wembley.
In front of a world record crowd, Argentina dominated for 50 minutes, taking advantage of two All Black sin-binnings as they played some scintillating rugby.
However Aaron Smith's try just before the hour proved the turning point, with Sonny Bill Williams' introduction making a massive difference as the world champions calmly came back for what was eventually a relatively comfortable win.
In a tournament that came alive with Saturday's shock win for Japan over South Africa, Argentina looked prime to record their first-ever win against the All Blacks, but after failing to press home their early dominance, they paid the price in the final quarter.
The game followed the expected script in the opening 20 minutes, New Zealand opening up a 9-0 lead, however Guido Petti's try sparked an incredible passage from Argentina who had the All Blacks on the ropes.
Eventually Aaron Smith's score, and a second try from Sam Cane, proved enough for the All Blacks, but the Pumas laid down a marker and won't fear anyone in what is potentially the easier side of the draw should they finish second in the pool.
New Zealand were put under pressure, and saw McCaw and Conrad Smith both sin-binned, but also showed why they are the best in the world when up against it, calmly fighting their way back to complete the win.
The world champions drew first blood with an early Dan Carter penalty, and things got worse for the Pumas on ten minutes when they lost a man to the bin.
Despite a powerful Pumas scrum five metres out from their own line, New Zealand were able to secure the ball and set up camp in the Argentina 22. Ben Smith's through-the-legs pass was reminiscent of Carlos Spencer 12 years ago, but after Julian Savea had been tackled, Argentina were penalised for slowing the ball. Aaron Smith tapped and went and was instantly tackled by Pablo Matera who was inevitably yellow-carded.
Carter added a second penalty to make it 6-0 to the All Blacks, with Argentina having barely ventured into New Zealand territory.
Argentina coped relatively well while down a man, but did concede a third penalty, converted by Carter, when they were caught offside in defence.
However on their first lengthy period of possession in All Black territory, Argentina scored a well-deserved try. Both forwards and backs made ground with ball in hand, number eight Leonardo Senatore was particularly involved. When he was stopped short, young lock Petti picked up and dived around the fringes to score.
He caught a boot to the head from Carter in the process, having to go off as a result. Nicolas Sanchez's conversion made it 9-7 midway through the half.
While Carter's offence wasn't intentional, McCaw could have been sin-binned in the build-up, coming in cynically from the side as Argentina piled forward. He was soon taking ten minutes off though after being spotted tripping Juan Martin Fernandez-Lobbe as he tried to take a tap penalty. TMO George Ayoub spotted the remarkably cynical act, and the All Black skipper was yellow-carded for only the third time in his long Test career.
Sanchez converted the penalty to give Argentina the lead, and the Pumas took advantage of their extra man to pile forward with some great continuity as the half drew to a close. Juan Imhoff's break had New Zealand scrambling, and when Conrad Smith dived off his feet to kill the move, he became the second All Black to go to the bin. Sanchez added three more points and Argentina led 13-9.
New Zealand showed their experience to earn a penalty while down to 13, Matera penalised for slowing down the ball, and Carter made it a one-point game with the last kick of the half.
Those three points from Carter were quickly cancelled out by Sanchez after the break, as New Zealand rushed up too quickly in defence following more good work from the Pumas.
Steve Hansen clearly wasn't happy with what he was seeing, and brought on Williams for Ma'a Nonu, the former league star almost making an instant impact. He shrugged off one tackle and was almost over, but after he was scragged, Nehe Milner-Skudder couldn't collect a trademark offload with the try-line at his mercy.
Milner-Skudder was hooked for that mistake, replaced by Beauden Barrett, but while the chance had gone, territory and possession was all New Zealand by this point. The Pumas held for as long as they could, but just before the hour, the All Blacks finally broke through.
Following a maul that had been shunted backwards, Aaron Smith peeled away and then stepped inside the despairing Tomas Cubelli to dive over and give his team the lead again. Carter's conversion made it 19-16 to the world champions.
From there Argentina never really threatened a comeback, and any hopes were extinguished when New Zealand worked some space out wide for Cane to stroll over.
They could have had more, but the Pumas defence held, and in fairness, anything more than the ten-point margin between the sides would have been unfair on Argentina.
New Zealand continue their record of never having lost a pool game, and despite some signs of weakness, showed all their experience to get the job done.
Man of the match: It's tempting to go with Agustin Creevy after an incredible all-action display, but we'll go for Sonny Bill Williams. He might have been lucky to make the squad, but his introduction turned the tide for New Zealand.
Moment of the match: The Aaron Smith try seemed to liberate New Zealand, having looked rattled for much of the opening 50 minutes. Tomas Cubelli knew its importance as he watched on helplessly having fallen for Smith's sidestep.
Villain of the match: Richie McCaw played the cartoon villain role, and his trip was surprisingly stupid from a player of his experience. The boos that rang out every time he appeared on the big screen were unnecessary though.
Pens: Sanchez 3
Yellow Card: Matera
For New Zealand:
Tries: A Smith, Cane
Cons: Carter 2
Pens: Carter 4
Yellow Cards: McCaw, Smith
Argentina: 15 Joaquin Tuculet, 14 Santiago Cordero, 13 Marcelo Bosch, 12 Juan Martin Hernandez, 11 Juan Imhoff, 10 Nicolas Sanchez, 9 Tomas Cubelli, 8 Leonardo Senatore, 7 Juan Martin Fernandez Lobbe, 6 Pablo Matera, 5 Tomas Lavanini, 4 Guido Petti, 3 Nahuel Tetaz Chaparro, 2 Agustin Creevy (c), 1 Marcos Ayerza
Replacements: 16 Julian Montoya, 17 Lucas Noguera, 18 Ramiro Herrera, 19 Mariano Galarza, 20 Juan Manuel Leguizamon, 21 Martin Landajo, 22 Jeronimo De La Fuente, 23 Lucas Gonzalez Amorosino
New Zealand: 15 Ben Smith, 14 Nehe Milner-Skudder, 13 Conrad Smith, 12 Ma'a Nonu, 11 Julian Savea, 10 Dan Carter, 9 Aaron Smith, 8 Kieran Read, 7 Richie McCaw (c), 6 Jerome Kaino, 5 Sam Whitelock, 4 Brodie Retallick, 3 Owen Franks, 2 Dane Coles, 1 Tony Woodcock
Replacements: 16 Keven Mealamu, 17 Wyatt Crockett, 18 Charlie Faumuina, 19 Victor Vito, 20 Sam Cane, 21 TJ Perenara, 22 Beauden Barrett, 23 Sonny Bill Williams
Venue: Wembley Stadium, London
Referee: Wayne Barnes (England)
Assistant referees: JP Doyle (England), Angus Gardner (Australia)
Television match official: George Ayoub (Australia)