The Blitzboks may have scored the first try, but were swatted aside 29-7 by the All Black Sevens in the third-place playoff of the New Zealand Sevens in Hamilton on Sunday.
Eventual champions Fiji also defeated the South Africans by the same margin in the semi-finals, with the Fijians going on to overwhelm USA 38-0 in the title decider.
Siviwe Soyizwapi opened the scoring in the third-place playoff against the hosts, but the Kiwis came roaring back through a brace by James Ng Shu, before Tim Mikkelson, Joseva Ravouvou and Sam Dickson dotted down to finish third in the tournament.
Earlier in the Cup semi-final, the Blitzboks were blown away by the Fijians, who produced a three-try blitz in the first half through Kalione Nasoko, Aminiasi Tuimaba and Vilimoni Botitu.
Kyle Brown also received a yellow card in the first half, and the South Africans could only a produce a consolation try through Selvyn Davids.
The Fiji victory sees them join USA at the top of the World Series log on 57 points, with New Zealand third on 54 and the Blitzboks trailing in fourth on 44.