The Blitzboks lost 17-7 to New Zealand in the Cup semi-finals of the Wellington Sevens, before thrashing Scotland 40-7 in the third-place play-off.
South Africa have never won the tournament in its 16-year history, and that run continued after being undone by the hosts, who went on to beat England 27-21 in the final.
The Blitzboks, who had beaten Kenya 19-5 in the quarter-finals, made a shaky start to their semi-final when Joe Webber scored an early try for the hosts. Referee Matt O’Brien then harshly yellow-carded Seabelo Senatla for repeated infringements, even though there had only been two penalties in the game.
But the Blitzboks were able to score while the speedster was off the field, through Kwagga Smith, to make it 7-7 at the break.
South Africa were heavily penalised at the breakdown in the second half, with Jack Goodhue scoring for New Zealand from a quick penalty tap.
The hosts then tried to kick a drop goal to put the result beyond doubt, but the ball hit the post. Cecil Afrika's rushed clearance kick came off the side of his boot, and resulted in a 20m try for 17-year-old Rieko Ioane.
The Blitzboks fell behind early against Scotland in the third-place play-off, but recovered through first-half tries by captain Kyle Brown, Warrick Gelant and a brace by Senatla. Branco du Preez added the extras to give his side a commanding 28-7 lead at the break.
Gelant, a former SA U20 star, added another just after the restart, before coach Neil Powell started to ring the changes. Further tries from Rayno Benjamin and Gelant rounded out the clinical display.
South Africa, who remain top of the World Series standings, will now head to Las Vegas, where they will bid to defend the title they won last year. They will be in Pool C with hosts USA, Japan and Portugal.
New Zealand 27 Australia 7
South Africa 19 Kenya 5
England 26 Fiji 21
Scotland 19 USA 15
England 24 Scotland 19
New Zealand 17 South Africa 7
New Zealand 27 England 21
World Series standings (after four rounds):
1. South Africa 76
2. New Zealand 69
3. Fiji 64
4. Australia 58
5. England 56
6. Argentina 47
7. Scotland 42
8. USA 36
9. Samoa 31
10. Wales 30
Photo: Anthony Au Yeung/Getty Images