The Blitzboks beat Chile, Wales and the USA to progress to the Cup quarter-finals of the Vancouver Sevens.
The South Africans were expected to struggle against the current World Rugby Seven Series leaders, who had pummeled them in Las Vegas last weekend.
However, the Blitzboks got off to a dream start when JC Pretorius was just able to hold onto a pass and cruise past Ben Pinkelman for his fourth try of the day.
The USA almost responded immediately when Carlin Isles was freed up out wide but the speedster was called back as replays showed the pass to him from Martin Iosefo was forward.
A brilliant play from Selvyn Davids, which saw him loop a lineout-style pass out to the wing, allowed Stedman Gans to go in for the Blitzboks second try, making it 14-0 at the break.
The USA were fastest out of the blocks in the second half as, after Isles broke the line and was brought down illegally, a quick-tap penalty was worked to the right and Steve Tomasin scored to make it a seven-point deficit.
South Africa gave themselves some important breathing space a couple of minutes later as Pretorius broke through and, while he was hauled in by Isles, had enough strength to shrug off the American’s tackle and score the decisive try.
— World Rugby Sevens (@WorldRugby7s) March 10, 2019
Earlier in the day, a hat-trick from Siviwe Soyizwapi and brace from Pretorius gave the Blitzboks a seven-try 43-0 win against Chile in their opening game of the tournament.
— World Rugby Sevens (@WorldRugby7s) March 9, 2019
Tries from Philip Snyman, Pretorius and Davids then allowed South Africa to beat Wales 19-10 and qualify for the quarter-finals with a game to spare.
The Blitzboks will face Argentina in the Cup quarters at 8:08pm on Sunday.