South Africa were 171 for five at the close after skittling Australia for 85 on the opening day of the second Test in Hobart on Saturday.
The Australians capitulated to their lowest total against South Africa at home with Vernon Philander taking five for 21 despite injuring his shoulder in a mid-pitch collision with Steve Smith, who remained unbeaten on 48.
At stumps, Temba Bavuma was not out 38 with Quinton de Kock on 28, with the Proteas leading by 86 runs.
Earlier, Australia's hopes of preventing South Africa from winning a third consecutive series Down Under suffered a major setback after recording their lowest total against the Proteas at home in Hobart on Saturday.
Steve Smith's hapless team were demolished for just 85, with Vernon Philander snaring five for 21 as South Africa seized control on just the opening day of the second Test.
At tea, the Proteas strengthened their hold with an unbroken stand of 43 with Stephen Cook on 23 and Perth centurion Dean Elgar not out at 17.
The capitulation revisited the nightmares of their miserable 47 in Cape Town in 2011 and England's demolition for 60 at Trent Bridge last year.
Only skipper Smith provided any backbone in his unbeaten knock of 48 as the Australians failed to back up their talk of rebounding from their comprehensive 177-run thrashing by the Proteas in the Perth series opener.
South Africa are on the verge of emulating the intimidating West Indies teams of the 1980s-1990s with three straight series wins in Australia after their convincing victory in Perth.
The Hobart rout also follows the first innings collapse of 10 for 86 in Perth when they squandered a 158-run opening stand to surrender meekly to the Proteas.
Cricket statisticians were in overdrive as Australia plumbed new lows in Hobart -- it was also their lowest total since their 76 at home against the West Indies in 1984.
David Warner was the barometer of an approaching Australian maelstrom when he recklessly slashed at a wide ball in Philander's opening over and was caught behind.
It was an irresponsible shot from the Australian vice-captain and things only got worse in Kyle Abbott's following over when recalled Joe Burns was trapped leg before wicket.
The home side lost both openers for just two runs and it was a steady procession from the wicket with only Smith offering any spirited resistance.
The Australians reached lunch at 43 for six after Usman Khawaja edged Philander to Hashim Amla at slip for four and Adam Voges was out next ball, caught behind by Quinton de Kock.
Callum Ferguson, who fought off a hat-trick ball after coming to the wicket in his first Test, was brilliantly run out for three by a direct throw by fielding substitute Dane Vilas while going for a second run.
Wicketkeeper Peter Nevill was the sixth wicket to fall after a DRS review of a lbw appeal off Kagiso Rabada with nothing going Australia's way.
Philander was forced to leave the field for shoulder treatment after a mid-pitch collision with Smith during a leg before wicket appeal, but returned after lunch.
Philander bowled newcomer Joe Mennie for 10 and JP Duminy took a screamer of a catch to dismiss Mitchell Starc, flinging himself one-handed to his right off Abbott.
Josh Hazlewood cracked two fours before he fell to a slips catch by Amla off Abbott.
De Kock took a blinding one-handed catch across the slips cordon to remove Nathan Lyon and end the Australian innings.
The South Africans earlier named Kyle Abbott in their only change in the absence of injured strike bowler Dale Steyn.
Australia dropped all-rounder Mitchell Marsh and gave Test debuts to batsman Ferguson at No.6 and paceman Mennie, while Burns replaced injured opener Shaun Marsh.
