South Africa have restricted Australia to just 154 all out in less than 42 overs of the second one-day international in Perth.
Morne Morkel grabbed the tourists' first wicket with just the fifth ball of the day as Quinton de Kock took a low catch from David Warner's edge.
Dale Steyn then got in on the act as Aaron Finch drove the ball into the hands of Morkel, before Shane Watson was trapped lbw in the 10th over.
Steven Smith soon followed as the fast and bouncy WACA pitch caused mayhem for the Australian top order, with Morkel relishing the conditions and taking five wickets in the process.
Mitchell Marsh was the only batsman to offer any kind of resistance, but he eventually fell for 67 to leave the hosts reeling at tea interval.
