Sonny Bill Williams turned from villain to hero as the All Blacks Sevens pipped South Africa 19-14 after the hooter and capped a triumphant start to the world series tournament in Wellington.

Cross-code star Williams, in his debut sevens appearance, was the central figure in the dying moments of the opening day’s final game, between two unbeaten powerhouse sides.

Entering late off the bench with his side 12-7 ahead, Williams threw an offload to nobody with a minute remaining which was pounced on by the Blitzboks, who hit the front through a converted Cheslin Kolbe try.

With time up and New Zealand close to their tryline, a sweeping move upfield was capped when another Williams offload put Joe Webber clear 40m out and ensured the tournament defending champions made it three from three in pool play.

The transition of All Blacks back Williams was always going to be the talking point and he let nobody down, scoring with his only touch off the bench in their 38-7 win over Russia.

The 30-year-old started against Scotland and was solid, if unspectacular, in their 27-7 win.

It was an encouraging debut for a player who has his sights set on selection for the Rio Olympics.

However, for pure output, it was hard to go past captain Tim Mikkelson – a sevens specialist – and rising 15-a-side loose forward powerhouse Akira Ioane as New Zealand’s best performers.

They have set up a quarter-final against Kenya, while South Africa will meet Australia, who were one of three unbeaten sides along with Fiji.

The world series defending champion Fijians unfurled the most accomplished displays, tallying 109 points to 24 in their hefty wins over pool runners-up Argentina, Wales and Japan.

It was the opposite for an under-strength Australian side, whose wins were all by seven points or less over Kenya, Canada and Portugal.

Pool C was the most competitive, with England beating France and the United States to secure top spot, before crashing to previously winless Samoa.

The USA qualified second by winning their sudden-death final pool game against France 29-21 to set up an unenviable quarter-final against Fiji.

New Zealand are gunning for a fifth win in the past six Wellington tournaments to alleviate a slow start to the world series.

They are sixth overall after injuries stymied their performances in the first two tournaments in December in Dubai and Cape Town.

QUARTER-FINALS:

* New Zealand v Kenya

* England v Argentina

* Australia v South Africa

* Fiji v United States