South Africa beat Australia by four wickets in the final over on Friday in the first of two Twenty20 matches.
Australia were put in to bat and totalled 166 for seven.
Opener David Warner made 38 off 29 balls before South Africa claimed three wickets in the 10th over to reduce the visitors to 71 for five at the Wanderers.
David Hussey then bludgeoned 88 not out off 44 balls with five fours and six sixes.
Left-arm seamer Wayne Parnell, 19, in only his third international match, picked up two for 29 while spinner Robin Peterson bagged three for 30.
Herschelle Gibbs began the run chase with 19 off 12 balls but South Africa lost their way when he was dismissed by Brett Geeves and slipped to 105 for five after 15 overs.
Albie Morkel provided the first signs of urgency as he smashed four fours and two sixes in his 37 off 19 balls before Mark Boucher pulled the first two deliveries of the final over from Geeves for four to finish with 36 not out in 22 balls.
Off-spinner Hussey took two for 21 and won the man of the match award for his fine all-round display.
The second game is at Centurion on Sunday.