A masterful 109 from Quinton De Kock and abysmal fielding has Australia facing a monster chase in Lucknow to avoid making a humiliating 0-2 start to the World Cup.
Australia pulled a selection surprise at the toss, naming West Australian gloveman Josh Inglis in place of the out-of-form Alex Carey as Marcus Stoinis replaced Cam Green.
But Pat Cummins was left to rue his decision to bowl first as South Africa backed up their record-breaking total from the first match with 7-311.
Glenn Maxwell was the pick of the Aussie attack, taking 2-34 and not conceding a boundary.
Cummins turned to Maxwell after six overs as De Kock and Temba Bavuma worked the quicks over with clever strokes.
The skipper then brought himself on in what appeared to be an inspired move as his opposite number, Bavuma, skied a leading edge miles into the air towards third man.
But Adam Zampa never got close.
Bavuma was handed another life as Inglis grassed a thick outside edge after it struck and rolled up his thigh.
The South African skipper was onto life number four as sub-fielder Sean Abbott fell over the boundary rope after catching a high ball.
He tried to flick the ball to Mitchell Starc but tossed it over his head.
Bavuma finally ran out of luck against Maxwell, picking out David Warner at deep mid-wicket for 35.
Australia began wrestling the momentum back, but De Kock ripped it out of their grasp, flick-scooping Josh Hazlewood for a maximum over fine leg before doubling the dose with a hook shot.
After making a century in the first match, Rassie van der Dussen made a casual start but handed Zampa his first wicket of the World Cup when he found mid-on advancing down the track on 26.
Cummins thought he had another soon after as Aiden Markram chipped a full toss back to him, but the Aussie skipper dropped the simple chance.
De Kock rubbed salt into the wound later in the over as he brought up his century with a huge six.
The South African began to suffer from fatigue as he tried to kick on, out reverse sweeping Maxwell onto his chest and into the stumps.
Markram battered Zampa to his half century before slicing a slower ball to point off Cummins on 56.
A double bluff short-ball from Hazlewood ended Klaasen’s night early as Australia wisely employed slower-ball tactics, slowing the Proteas pace.
Starc added a 5th dropped catch in the deep when his elbows hit the turf before Stoinis added the worst of the night, dropping a skyball in the ring that hit his chest.