Rilee Rossouw blazed 78 on his Twenty20 debut and shared a 129-run second-wicket stand with Quinton de Kock, who scored 46 from 39 balls, as South Africa opened the three-match series with a seven-wicket win over Australia.
Australia batted first on Wednesday and was restricted to 144-6 from 20 overs, with Shane Watson scoring 47 and James Faulkner unbeaten on 41.
It was nowhere near enough on a batting-friendly pitch at the Adelaide Oval, with the South Africans reaching 145-3 with an over to spare.
Rossouw reached his half century from 32 balls and finished with 78 from 50 deliveries, including three sixes and seven boundaries.
The second game will be on Friday at Melbourne.