The New Zealand sevens team were left to contemplate a third successive failure on home soil after South Africa adopted the role of party pooper at the Wellington leg of the IRB Series, storming to an historic win at WestpacTrust Stadium on Saturday.

South Africa recorded their first tournament win in the third cycle of the world circuit, edging Samoa 17-14 in a tense final later described as a watershed victory by coach and Springbok World Cup hero Chester Williams.

New Zealand motored through pool play, racking up 147 points in three lopsided encounters on Friday. They brushed aside Wales 78-0 in the quarters on Saturday but were found wanting when they struck South Africa, their first tough encounter of the weekend.

South Africa were emphatic 26-10 semifinal victors, silencing a home crowd prematurely anticipating victory after Fiji and Australia made shock early exits.

However South Africa, as their cricketers did across the Tasman, had more than New Zealand's measure, running in four long-range tries after regularly outflanking a porous New Zealand defence.

Their superiority was freely acknowledged by the New Zealand camp who were undone by the South Africans extreme pace and swarming defence.

"They got outside our defensive line, spread it wide and exposed us, they opened up the holes in the middle," Karl TeNana said.

"We've got to give it to South Africa. They worked us out and we couldn't combat it."

South Africa's win trimmed New Zealand's lead at the top of the IRB Series to eight points with six of the 11 rounds remaining. The failure of Fiji and Australia was of little consolation for the New Zealanders who had hoped to supply captain Eric Rush with a fitting farewell in what could be his Wellington swansong.

The reintroduction of Rush, TeNana and playmaker Amasio Valence paid dividends early but South Africa, led by former Bulls Super 12 player Paul Treu and livewire pivot Brent Russell piled on the agony as early as the first minute.

Jean de Villiers (pictured) rounded off a straightforward back move before Russell strolled over to give South Africa a 14-5 halftime advantage that never looked liked being reeled in.

TeNana said New Zealand's easy passage into the semis may have counted against them. "The quarterfinal against Wales didn't really prepare us. We were on a high and we never had our defence tested," he said.

Rush agreed, suggesting their "feet weren't on the ground" after the romp over Wales. Samoa lost to South Africa in pool play Friday but made a better fist of the final and were only denied by staunch defence in the dying stages.

Muller and Russell built a 10-0 halftime lead and despite some aggressive tackling and a try a minute after the resumption by Notise Tauafao, South Africa clung on.

De Villers scored to extend the lead to 17-7 and although Samoa finished strongly with a late converted try to Uale Mai the South Africans successfully ran down the clock.

Williams credited the win to superb teamwork and fitness levels, two aspects he had worked on since taking charge in November. He cited their narrow 14-12 semifinal loss to New Zealand in Brisbane last weekend as a turning point.

That performance gave the side the confidence to foot it with the Kiwis. "That was a turning point and now we want to win another tournament or two."

The only blot on the win was the loss of De Villiers with hip and pelvic injuries. He was taken to Wellington Hospital for treatment.

Samoa made the final with a controlled 36-5 win over surprise packet England. Fiji slumped remarkably on the final day, crashing to England 19-14 in the quarters and then Argentina, 21-12, in the Plate semi.

Australia, missing the Super 12 players that carried them through last weekend never fired, bowing out to South Africa 28-0 in the quarters and Wales 19-14 in a pulsating Plate semi.

Argentina won the Plate final with a 52-12 crushing of a tired Wales. France took the Bowl final, defeating Canada 26-5 and the Cook Islands claimed the Shield final with a 38-14 victory over Papua New Guinea.

The next leg of the series is in Beijing, China, on March 16-17.

Leading points (after five of 11 rounds): New Zealand 80, South Africa 72, Samoa 56, Fiji 46, Argentina 46, Australia 40. - Sapa-NZPA