Scoring 11 tries in the process, coach Chean Roux’s youngsters showed incredible skill with ball in hand and the South Americans had no answer to their potent attack.
Wing Gianni Lombard and hooker Johan Grobbelaar both crossed the tryline twice as South Africa made sure they finished at the top of Pool C.
Heading into next week’s semis, Roux says: “We treated this match as a quarterfinal and the players responded very well.
“All credit must go to them. I think they delivered a fantastic performance.
“But we have achieved nothing yet.
“We have already started with the planning for the next game.”
He adds: “The players have worked hard. But this means nothing if we do not win the next match.”