The All Blacks floored the Boks with 17 points in just five first-half minutes to silence their critics.
It was the culmination of a thrilling first full day of action at the tournament in Japan after Australia came from behind to beat Fiji 39-21, and France scraped past Argentina 23-21.
In Yokohama, the venue for the final on November 2, New Zealand went behind to an early penalty but they turned the game on its head with two silky tries to lead shell-shocked South Africa 17-3 at the break.
George Bridge went over after a breathtaking counter-attack, and Scott Barrett galloped in for New Zealand’s second following another flowing move when Anton Leinert-Brown stepped past a group of Springbok defenders.
France and Argentina came to blows at the end of their match after Emiliano Boffelli’s last-gasp penalty miss allowed Les Bleus to sneak home by just two points.
Gael Fickou and Antoine Dupont both scored brilliantly as France led 20-3 at the break, before Argentina came storming back with two near-identical catch-and-drive tries to Guido Petti Pagadizaval and Julian Montoya.
Benjamin Urdapilleta slotted two penalties to give Argentina a 21-20 lead but Camille Lopez’s cool drop goal put France back in front, and the unfortunate Boffelli missed his chance for glory when he put his penalty wide.
“We never controlled the game and we never controlled the ball in the second half but we are very proud of the first half, because we were very clinical and when we play like this we are very dangerous,” said France captain Guilhem Guirado.
The indoor Sapporo Dome witnessed some bone-crunching collisions as Fiji led Australia 21-12 early in the second half, before replacement scrum-half Will Genia inspired Australia’s recovery and bonus-point win.
Tolu Latu crashed over twice, and Samu Serevi and Marika Koroibete also crossed in the second half following scores by Michael Hooper and Reece Hodge in a helter-skelter first period.
“They’re such a dangerous team, we knew that very well,” said Wallabies coach Michael Cheika. “It’s what we expected (but) we probably didn’t expect to be so far behind.
“We made a few errors that let them into it but we recomposed ourselves, went back to basics and were able to get it done.”
Also on Saturday, tournament organisers warned teams about possible disruption from an approaching typhoon and closed two fanzones in southwestern Japan as a precaution.
Typhoon Tapah bashed Japan’s southern Okinawa islands on Saturday, cutting power to more than 15,000 homes and grounding hundreds of flight.
The storm – packing wind gusts of up to 180 kilometres per hour – is now heading north and is expected to move through the sea separating South Korea and western Japan. (AFP)