GALLERY: Fans at the Australia Sevens
The Blitzbokke won 21-7 after the scores were tied at 7-7 at half-time.
Earlier, the Blitzbokke beat the USA 17-12 and Japan 31-7 to top their Pool and set up a quarter-final clash against France on Saturday.
New Zealand, Samoa, Wales and South Africa were unbeaten in pool play on the first day of the Gold Coast Sevens tournament.
World champions New Zealand topped Pool A in the opening round of the International Rugby Board world series on Friday with a decisive 28-5 win over Fiji after earlier beating Kenya 26-5 and Nuie 38-0.
Wales upset England 21-7 to top Pool D, also beating Tonga 24-7 and Scotland 14-12.
South Africa shocked hosts Australia 21-7 in the final match in Pool B, scoring two second-half tries after the teams had been locked 7-7 at halftime. The South Africans also beat the United States 17-12 and Japan 31-7.
Samoa topped Pool C, beating Papua New Guinea 38-0, France 24-14 and Argentina 29-0.
In quarterfinals on Saturday New Zealand will play England, Samoa will play Australia, Wales will play Fiji and South Africa will play France.
Results:
Pool A
Fiji 38, Niue 0
New Zealand 26, Kenya 5
New Zealand 38, Niue 0
Fiji 26, Kenya 7
Kenya 19, Niue 7
New Zealand 28, Fiji 5
Pool B
Australia 33, Japan 0
South Africa 17, United States 12
South Africa 31, Japan 7
Australia 22, United States 7
United States 21, Japan 0
South Africa 21, Australia 7
Pool C
France 34, Argentina 14
Samoa 38, Papua New Guinea 0
Argentina 33, Papua New Guinea 0
Samoa 24, France 14
France 33, Papua New Guinea 5
Samoa 29, Argentina 0
Pool D
Wales 24, Tonga 7
England 24, Scotland 5
Wales 14, Scotland 12
England 19, Scotland 0
Scotland 14, Tonga 12
Wales 21, England 7