Robert Ebersohn scored two first half tries for the Springbok Sevens on the ground where he helped his team to Cup success last year.
Renfred Dazel and Vuyo Zangqa scored their other tries, while Adam Vardey touched down for the islanders.
Kenya, who defeated New Zealand in the quarter-finals at Hong Kong last weekend, also got their campaign off on a winning note. Brothers Collins Injera and Humphrey Kayange touched down in either half for the Kenyans as they ran out 12-5 winners against Japan in the opening match of the tournament. Tongan-born player Alisi Tupuailei scored late on for Japan.
With three events still to complete - in Adelaide, London and Edinburgh - Paul Treu's team currently lead the way in the World Series with 84 points, 16 clear of England (68) with Fiji (62), New Zealand (60) and Argentina (56) all still well in contention.
The Bok Sevens will be in action in two matches on Saturday, against Japan and then Kenya in the last match of the day.
05h57: SA vs. Japan
09h40: SA vs. Kenya
