A heroic double century from resurgent opener David Warner has powered Australia to a 197-run lead at the MCG, crushing weary South Africa's spirit in the Boxing Day Test.
Australia smashed 2-341 on Tuesday to go to stumps at 3-386 and in sight of their first Test series win against the Proteas on home soil in 17 years.
Warner ended a drought of almost three years without a century by making it a double in his 100th Test. He retired hurt on 200 in the final session.
On becoming the eighth Australian to score a double ton at the MCG, an emotional and exhausted Warner was helped off the field by medical staff, suffering sun stress and cramps after batting in oppressive conditions
But the 36-year-old's job was more than done as Warner put on a 239-run third-wicket stand with Steve Smith (85), the highest partnership between Australia's most dominant batters of their generation.
The aggressive left-hander picked the right match to return to form, becoming the second Australian after Ricky Ponting in 2006 to reach three figures in his 100th Test.
Warner entered the traditional blockbuster under extreme pressure after averaging just 20.61 this year but conjured a trademark innings for his 25th Test century, his first since January 2020 against New Zealand.
In-form No.5 Travis Head (48 no) and wicketkeeper Alex Carey (9 no) will resume on Wednesday as Australia attempt to quickly build on their imposing lead.
"The boys were cramping left, right and centre," Smith said. "So, difficult (conditions) but nice to get us to the position where we are now. I think we're in a nice spot.
"Hard to believe I was the last wicket (because of the two retired hurts). I was looking up and (spinner) Nathan Lyon was padded up next to me and we're three (wickets down)."
However, things aren't perfect for Australia as they deal with injury concerns to emerging allrounder Cameron Green and star quick Mitchell Starc.
A day after his first Test five-wicket haul, Green was forced to retire hurt on six after being hit on the index finger by Proteas quick Anrich Nortje. He was taken to hospital for scans.
That incident came after Starc damaged the middle finger on his bowling hand attempting a difficult diving catch in the deep on Monday.
Starc has been cleared to bowl in South Africa's second innings but the tall left-armer is understood to be in doubt for the third and final Test at the SCG next week.
The Proteas, demolished in two days at the Gabba last week, are heading for their first Test series loss in Australia since 2005-06 after succeeding in their previous three visits.
South Africa's inexperienced batting line-up has not given their fearsome pace attack of Kagiso Rabada, Nortje, Lungi Ngidi and Marco Jansen anywhere near enough runs to defend after faltering for their seventh-straight innings under 200.
Smith was dropped by Proteas wicketkeeper Kyle Verreynne on nine, and added another 76 runs on a brutal day for the visitors.
Verreynne, who scored a vital 52 on Monday to add to an impressive 64 in Brisbane, also put down a regulation catch off Warner on 122.
The only wicket of the first two sessions of the day fell when Marnus Labuschagne (14) was run-out for the fifth time in his 32-Test career after a stop-start mix-up with Warner.
A rare bright spot for the Proteas was fiery quick Anrich Nortje (1-50) regularly bowling deliveries exceeding 150km/h.
However, Nortje was involved in a bizarre incident when the host broadcaster's spider cam collided with him when he was walking to his fielding position. He was knocked over but not hurt.
