The Blitzboks backed up their win over Argentina, with victories over Japan and France on day two of the Hong Kong Sevens.
South Africa will face Australia in the Cup quarter-finals on Sunday.
In the first of the two matches, the Blitzboks blanked out Japan 27-0. Tries from Werner Kok, Stephan Dippenaar and Justin Geduld, and a conversion by Branco du Preez, handed the Blitzboks a 17-0 advantage at the interval, despite losing Philip Snyman to the sin bin.
A strong drive saw Kwagga Smith crash over to land the first blow in the second half, before Rosco Speckman sealed the match with his first international try.
The Blitzboks had to work harder to oust France 29-7, after captain Kyle Brown's unconverted try was cancelled out by Les Bleus' Stephen Parez, who also stepped up to nail the conversion, which put his team ahead by two.
Seabelo Senatla continued his impressive try-scoring form to edge the Blitzboks ahead, as they led 12-7 at the break.
They shrugged off a shaky first-half performance, when first Kok dotted down, before a Senatla brace, to complete his hat-trick, sealed the Springbok Sevens' passage into the quarter-finals.
Sunday's Cup quarter-finals (to start 4:58am SA time):
Fiji vs England
South Africa vs Australia
USA vs Samoa
New Zealand vs Argentina
Photo: Aitor Alcalde/Getty Images