|New Zealand (12) 26|
|Tries: A Smith, Cane Cons: Carter 2 Pens: Carter 4|
|Argentina (13) 16|
|Tries: Petti Pagadizabal Con: Sanchez Pens: Sanchez 3|
Reigning champions New Zealand were shaken to the core by Argentina in their World Cup opener, but weathered the storm to secure a gritty victory.
The rattled All Blacks lost two players to the sin bin in the first half, captain Richie McCaw and Conrad Smith, and the Pumas led 13-12 at the break.
But New Zealand made changes early in the second half and it made all the difference.
Scrum-half Aaron Smith scampered over for New Zealand's first try after 56 minutes before a Sam Cane score settled things.
A stirring spectacle was witnessed by 89,019 fans at Wembley Stadium, a new record for the tournament.
Argentina had never beaten the All Blacks in 21 previous matches and few expected them to get close to a side boasting 1,013 Test caps, the most in Test history.
And for the first 20 minutes it looked like the Pumas' passion might be their undoing, with flanker Pablo Matera sin-binned for not retreating and All Blacks fly-half Dan Carter kicking his side into a 9-0 lead.
But in Matera's absence, Argentina started getting their big runners on the ball and when lock Guido Petti Pagadizabal rumbled over for a try from close range, it changed the complexion of the game completely.
McCaw, playing in his 143rd Test, was shown a yellow card for a cynical trip on Juan Martin Fernandez Lobbe, after which Nicolas Sanchez kicked the Pumas into a 10-9 lead.
With McCaw looking on, and being roundly booed by a rowdy Argentine contingent every time he appeared on the big screen, Argentina took the game to New Zealand.
Magic man Hernandez
Knowing they did not have the size to match the All Blacks through the middle, Argentina instead used the width of the pitch intelligently and kept the ball alive, light-fingered centre Juan Martin Hernandez typifying their approach.
There was also some bullocking defence from the Pumas, one tackle by winger Santiago Cordero on All Blacks number eight Kieran Read drawing a huge roar from the crowd.
With Argentina assailing New Zealand's try-line shortly before half-time, Conrad Smith was shown a yellow card for hands in the ruck and when Sanchez increased Argentina's lead to 16-12 shortly after the restart, it looked like another almighty upset might be on.
Strength in depth
But when All Blacks head coach Steve Hansen started emptying his bench, the pendulum slowly began to swing back in his side's favour.
Sonny Bill Williams, on for the strangely flat Ma'a Nonu, almost put Nehe Milner-Skudder over with a fine offload but the Hurricanes winger snatched at the ball two metres from the Argentina try-line.
But following more major surgery, which included both props being replaced and a re-jig in the back-line, Aaron Smith finally breached Argentina's desperate defences, picking up from the base of the scrum and scuttling over.
New Zealand could have scored several tries in the last 20 minutes but Read butchered one chance, failing to find an unmarked McCaw on the left wing, before Cane dropped an inside pass from Aaron Smith with the try-line begging.
But Cane did wrap things up a couple of minutes later, by which time the Argentines were out on their feet, albeit their spirits not extinguished.
What's to come?
New Zealand continued their proud record of never losing a pool game in a World Cup, while Argentina will be confident of advancing to the quarter-finals.
The All Blacks' next game is against Namibia at the Olympic Stadium in London on Thursday, while Argentina next face Georgia in Gloucester on Friday.
'It's magic to play at Wembley'
New Zealand captain Richie McCaw said: "I guess that's what you expect first up. I thought that second half was a lot more clinical.
"It's a magic place to play here at Wembley, it's one of the great grounds to play at.
"It's been a while since our last game and we've been over here for 10 days or so, so we were itching to get out there and get started. We'll have to make a few improvements but that's the nature of rugby."
|More from rugby:|
|Get World Cup alerts direct to your phone|
|World Cup schedule|
|Who's going to win the World Cup?|
|Who will star at the World Cup?|
|What is life like as an All Black?|
|For the latest rugby union news, follow @bbcrugbyunion on Twitter|
New Zealand: Ben Smith; Nehe Milner-Skudder, Conrad Smith, Ma'a Nonu, Julian Savea; Dan Carter, Aaron Smith; Kieran Read, Richie McCaw (capt), Jerome Kaino; Sam Whitelock, Brodie Retallick; Owen Franks, Dane Coles, Tony Woodcock
Replacements: Beauden Barrett for Milner-Skudder (51), Sonny Bill Williams for Nonu (46), TJ Perenara for A. Smith (69), Wyatt Crockett for Woodcock (46), Keven Mealamu for Coles (68), Charlie Faumuina for O. Franks (51), Victor Vito for Retallick (71), Sam Cane for Kaino (63).
Sin bin: McCaw (30), C. Smith (37).
Argentina: Joaquin Tuculet; Santiago Cordero, Marcelo Bosch, Juan Martin Hernandez, Juan Imhoff; Nicolas Sanchez, Tomas Cubelli; Leonardo Senatore, Juan Martin Fernandez Lobbe, Pablo Matera; Tomas Lavanini, Guido Petti; Nahuel Tetaz Chaparro, Agustin Creevy (capt), Marcos Ayerza.
Replacements: Lucas Gonzalez Amorosino for Tuculet (70), Jeronimo de la Fuente for Sanchez (69), Martin Landajo for Cubelli (62), Lucas Noguera for Creevy (70), Ramino Herrera for Tetaz Chaparro (55), Mariano Galarza for Petti Pagadizabal (23), Juan Manuel Leguizamon for Matera (59), Julian Montoya for Senatore (65).
Sin Bin: Matera (10).
Referee: Wayne Barnes.