Dragons RFC scrum half Gonzalo Bertranou started the game but could not stop South Africa securing a bonus-point win over Argentina in Buenos Aires to keep up the pressure on leaders New Zealand at the top of the Rugby Championship.
Tries from Jaden Hendrikse, Damian de Allende, a double from Malcolm Marx and a penalty try gave the Springboks victory.
The Springboks and All Blacks are level on 14 points with New Zealand leading on points difference (+41 v +28).
In the final round, South Africa face Argentina in Durban on Saturday after New Zealand host Australia in Auckland.
South Africa controlled the first half and led 22-6 at the break before Argentina came back in the final 15 minutes, closing the gap to two points at 22-20. But the visitors held their nerve to secure the win.