Skipper Elgar out cheaply again as Australia chase series sweep
Australia enforced the follow-on after dismissing the Proteas for 255 - 21 short of their target - and knocked over out-of-form skipper Dean Elgar cheaply again in South Africa's second innings.
South Africa were 46 for one at the interval with the odds favouring a draw but Australia still with an outside hope of an astonishing victory to complete a series whitewash.
"It's all about patience, building pressure and momentum with catchers around the bat," senior Australia batsman David Warner said.
"It always goes down to the last hour in Test cricket."
Sarel Erwee was not out 18 with Heinrich Klaasen on 18 at the interval and heading into the final session of the rain-hit Test.
Elgar fell for the fourth time in the series to a leg-side catch by wicketkeeper Alex Carey for 10.
Rival captain Pat Cummins peppered him with a rising delivery and targeted Elgar's technical flaw on his hips for yet another cheap dismissal.
Elgar finished a miserable series with 56 runs from six innings at an average of 9.33, raising yet more questions about his future as South Africa's Test skipper.
Josh Hazlewood earlier made a crucial double wicket breakthrough to help wrap up South Africa's first innings for 255, their highest innings total of a dismal series.
He removed the stubborn Keshav Maharaj leg before wicket for 53 off 81 balls, ending a 85-run partnership with Simon Harmer.
Hazlewood then struck again removing the stoic Harmer, bowling him off an inside edge for 47 from 165 balls.
Nathan Lyon ended the Proteas innings with a superb diving caught and bowled off Kagiso Rabada for three.
Hazlewood finished with four for 48 while his pace partner Pat Cummins took three for 60.
Part-time off-spinner Travis Head made the initial breakthrough on the final day having Marco Jansen caught behind by Carey for 11.
Australia are bidding for a series clean sweep to seal a place in the World Test Championship final in London in June.
Australia are 2-0 up in the series after winning the opening Test by a six-wicket rout in Brisbane inside two days, then hammering the Proteas by an innings and 182 runs in Melbourne.
