Argentina's hopes of making a bright start to the match were dealt a blow early on as Tomas Cubelli was sent to the sin bin for deliberately slowing the ball as the Pumas tried to capitalise on an early turnover.
It did not take the two-time world champions long to exploit their man advantage as JP Pietersen spotted a gap out wide, grounding the ball in the corner for his fifth try of the tournament.
Bryan Habana, who will become the outright top try-scorer in the history of the Rugby World Cup if he crosses the line this evening, came close to extending the Springboks' lead as the winger chased down a kick forward before diving over, but the replays confirmed that he did not get the ball down.
Cubelli tried to make amends for his yellow card with a run into South Africa territory, but the South American side could not force the ball across the line, while Handre Pollard added two penalties before the interval to extend South Africa's lead further.
Habana thought that he was over again as the interval approached, but he was down short as he looked to break Jonah Lomu's record, leaving Pollard to boot the ball through the posts again moments later.