Captain Luciana Aymar, recognised as the world's best player, led from the front with two goals - both courtesy of her superb control in the circle - as South Africa were left reeling after just 35 minutes of their London 2012 campaign.
Aymar's brilliant dink over a defender's stick allowed her to fire an eighth-minute penalty corner through the legs of goalkeeper Marietta Rix.
Another corner saw Josefina Sruoga add the second after Rix half-saved but failed to clear the ball.
South Africa briefly gave themselves a chance with a swift counter-attack from which Jen Wilson drilled in a right-wing cross for the diving Dirkie Chamberlain to convert.
But their joy was short-lived as Daniela Sruoga's cut-back was fired home by Martina Cavallero, more Aymar trickery at a penalty corner breakdown brought the fourth before Carla Rebecchi smashed home an angled reverse-stick shot just before the interval.
The world number twos eased up in the second half but in the closing minutes Noel Barrionuevo and Silvina D'Elia each put away a penalty corner.
Aymar said: 'Winning the first game will help us in strengthening the group dynamic.
'It was a tough game because it was our first game. There were a lot of nerves and it's good that we won.
In the day's other games, New Zealand beat Australia 1-0, Netherlands overcame Belgium, China bettered Republic of Korea, Great Britain go their campaign off to a winning start against Japan and Germany beat the USA 2-1.