Johannesburg - South Africa dropped one place in the overall standings after lifting the Plate in the fourth leg of the Sevens World Series in Wellington, New Zealand, on Saturday.
Having gone unbeaten on the opening day, the Blitzbokke were relegated to the second-tier competition with a 21-5 loss to Fiji in the Cup quarter-finals.
They were given a scare in the Plate semi-finals, narrowly edging past Canada 21-19, but bounced back to thump Tonga in the final.
Canada struck early, dotting down their first try in the second minute, but South Africa hit back to lead 14-7 at half-time.
The Canadians fought hard, scoring twice in the second period, but the Blitzbokke managed to hold them off for a 21-19 victory.
Cecil Afrika, returning to action after he was rested in the last pool game, scored two tries in the final as Tonga were handed a 24-0 whitewash.
South Africa fell to fourth in the series standings - behind New Zealand, Fiji and England - with 61 points.
The fifth leg, a three-day event, will be held in Las Vegas next week.
Results on Saturday from the New Zealand Sevens, fourth leg of the International Rugby Board World Series:
New Zealand 22, France 7
England 26, Tonga 7
Samoa 15, Canada 12
Fiji 21, South Africa 5
New Zealand 17, England 12 (Extra-time))
Fiji 28, Samoa 5
Playoff for third
England 21, Samoa 12
New Zealand 24, Fiji 7
Tonga 15, France 7
South Africa 21, Canada 19
South Africa 24, Tonga 0
Kenya 14, Scotland 5
Wales 10, United States 0
Australia 33, Japan 5
Argentina 28, Cook Islands 0
Kenya 17, Wales 7
Australia 24, Argentina 12
Kenya 12, Australia 7
Scotland 14, United States 12
Cook Islands 17, Japan 10
Scotland 19, Cook Islands 17
Standings after four of eight rounds:
New Zealand 73 points, Fiji 70, England 64, South Africa 61, France 49, Samoa 47, Australia 45, Wales 41, Argentina 33, Scotland 26.