For South Africa, Anrich Nortje took two wickets while Kagiso Rabada, Keshav Maharaj and Tabraiz Shamsi got one each.
Earlier, Electing to bowl, Australia restricted South Africa to a meagre 118 for nine.
Aiden Markram scored 40 for the Proteas after their top-order crumbled. Kagiso Rabada was the next best batter for them with an unbeaten 19-run knock at number eight.
Fast bowlers Josh Hazlewood (2/19) and Mithcell Starc (2/31) took two wickets apiece while spinner Adam Zampa (2/21) also accounted for two batters.
- South Africa: 118 for 9 in 20 overs. (A Markram 40, K Rabada 19 not out; J Hazlewood 2/19, A Zampa 2/21).
- Australia: 121 for 5 in 19.4 overs (Steve Smith 35, Anrich Nortje 2/21).