For the first time on the current Australian tour of South Africa, the hosts won the toss and chose to field first.
Dale Steyn started off well, restricting Australia to two runs off the first over, and then Wayne Parnell got the important breakthrough in the next over, when he bowled Michael Clarke for two.
Ricky Ponting made just one run before he was caught by Johan Botha off Albie Morkel in the fourth over.
But the explosive David Warner and the equally explosive David Hussey put on 54 for the third wicket off 35 balls. Robin Peterson had a hard time in his first over, with Hussey hitting him for a four and then a massive six that sailed into the Unity Stand, and Peterson's first over cost 12 runs.
However, three wickets fell in his next over, which went for just one run.
He caught David Warner off his own bowling for 38, and Michael Hussey was run out by skipper Johan Botha off the next. The third wicket to fall in the over was that of Brad Haddin, who was caught on the long-off boundary by Albie Morkel without scoring.
David Hussey and Cameron White joined forces, with a sixth wicket stand of 45, before Peterson struck again in his final over, with White well caught at deep midwicket by JP Duminy for 16.
Hussey, meanwhile, achieved his maiden T20 50 off 25 balls, and reached his highest score. He smashed five fours and six sixes.