The BlitzBoks will face Fiji in the Cup Final at the Hamilton Sevens on Sunday.
The South Africans were too strong for Australia in their Cup semifinal, while Fiji edged hosts New Zealand in the other semifinal on Day Two.
Australia 5-24 South Africa
South Africa did enough to beat Australia in their semifinal and book a place against Fiji in the Cup Final.
Tries from Cecil Afrika and Seabelo Senatla gave the BlitzBoks a 10-0 lead before Australia hit back just before half-time to reduce the deficit to five points.
However, the BlitzBoks were just too good to overtake in the second half with another try from Afrika and one from Albertus Smith securing a 24-5 win.
Fiji 14-12 New Zealand
Fiji ended New Zealand's hopes of winning a tournament in front of their home fans.
Fiji took an early 7-0 lead before New Zealand got their first score a few minutes later. At half-time it was 7-5 in favour of Fiji.
New Zealand took the lead early in the second half, but Fiji had the final say with another converted try in a tense finish.
Fifth place semifinals:
Kenya 33-19 Scotland
Scotland raced to a 14-0 lead, but they allowed Kenya to hit back with two tries themselves soon after and it was 14-14 at the break.
Kenya turned on the gas in the second half and they outscored Scotland by three tries to one to eventually win 33-19.
Samoa 22-17 England
England took an early lead, but it was Samoa who finished the half stronger with two tries for a 12-5 lead at the break.
Both sides scored two tries in the second half, but it was Samoa who waked away with a 22-17 victory.
Challenge Trophy semifinals:
USA 42-12 Papua New Guinea
The USA brought Papua New Guinea back down to earth with a 42-12 thrashing in their Challenge trophy semifinal.
The USA were in a commanding position at the half-time break after three converted tries and a 21-0 lead.
It was more of the same in the second half with the USA replicating their try-scoring form in the second half. PNG did manage to cross the whitewash on two occasions.
Canada 12-14 Argentina
It a tight match it was Canada who opened the scoring with an unconverted try.
However, it was Argentina who had a 7-5 lead at the break with a converted try a minute before half-time.
Both sides scored a try in the second half with Argentina walking away with a narrow 14-12 win in the end.
Thirteenth place semifinals:
Spain 14-19 France
Spain got things rolling with the first score of the game before France ran in two tries just before the break to lead 12-7 at half-time.
France extended their lead in the second half with a third try before Spain got a consolation score before full-time to go down 14-19.
Wales 33-7 Russia
Wales were ruthless in their encounter with Russia in the first thirteenth-place semifinal.
It was one-way traffic in the first half with Wales running in three tries to lead 19-0 at half-time.
Wales scored another two tries in the second half to just the one from Russia to win 33-7 in the end.