Pat Cummins worked wonders with the old ball to spark an astonishing Australian fightback on day one of the third Test, claiming four quick wickets as South Africa slipped to 8-266 at stumps.
The Proteas won the toss and marched to 2-220 in Thursday's final session, with Dean Elgar and AB de Villiers threatening to bat their side into a position of complete dominance in Cape Town.
Elgar will resume day two on 121, having weathered a painful blow to the helmet and made the most of a simple chance on 53 that Nathan Lyon put down at point.
But the opener was unable to stop a collapse of 6-37, adding just 12 runs amid the incredible turnaround.
The carnage started when de Villiers fell for 64, chipping a catch to David Warner at mid-off to become the first of four victims in a game-changing spell from Cummins.
Cummins, some six and a half years after announcing himself as a future superstar with a sparkling Test debut at age 18 in South Africa, removed de Villiers, Faf du Plessis, Temba Bavuma and Quinton de Kock in a burst of 4-7.
It was an eventful day for Cummins, whose conduct was questioned by the host broadcaster after he appeared to accidentally stand on the ball.
"Accidentally on purpose," former Proteas captain Graeme Smith quipped in commentary, inferring the express paceman was illegally looking to scuff one side of the pill.
The incident - one of many in a series stacked with dramatic cricket, spiteful spats and cantankerous claims - unfolded in front of the standing umpire.
Steve Smith delayed taking the second new ball when it was first available. It proved a smart call, with Vernon Philander edging a full delivery from Mitch Marsh soon after.
The tourists celebrated the dismissal of Philander vociferously, with umpires having a long chat with Warner afterwards.
Tim Paine had previously told Philander to "switch the phone off", sledging the paceman about last week's supposedly-hacked tweet that attacked Smith.
Keshav Maharaj offered little resistance, hitting the seventh ball he faced straight to Cameron Bancroft in the covers, but Kagiso Rabada fared much better.
Rabada finished six not out, having almost offered Smith his fourth slips catch of the day while on zero.
Rabada, whose two-Test ban for making physical contact with Smith was overturned earlier this week, was given a standing ovation when he walked out to bat.
Cummins worked both du Plessis and Bavuma over beautifully, creating apprehension in the batsmen's minds then earning the reward when they prodded forward to pinpoint deliveries.
De Kock's downfall was a loose pull stroke, with the edged flying straight to Paine.
Josh Hazlewood dismissed Aiden Markram and Hashim Amla, and would have had a third wicket if not for Lyon's dropped catch.
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