Janneman Malan hit his maiden international hundred as South Africa moved into an unassailable 2-0 lead in the one-day series against Australia with a six-wicket win at the Mangaung Oval.
Opener Malan had endured an ODI debut to forget in the previous match, dismissed lbw for a first-ball duck by Mitchell Starc, but made amends on Wednesday, finishing up unbeaten on 129.
JJ Smuts and Heinrich Klaasen – who made a century last time out – made useful contributions as the Proteas impressively overhauled Australia's total of 271 all out despite losing Quinton de Kock to the third ball of their reply.
The South Africa skipper was once again cleaned up by Starc, who had also bowled the left-hander twice during the recent Twenty20 series between the teams.
However, Smuts helped put on 91 for the second wicket - making 41 from 64 deliveries - and while Kyle Verreynne fell cheaply, Klaasen followed up his knock of 123 not out on Saturday with a valuable 51.
Adam Zampa (2-48) dismissed Klaasen to give Australia hope, yet David Miller (37 not out from 29 balls) shared in an unbroken stand of 90 to steer the hosts to their target with nine balls to spare.
Malan hit seven fours and four sixes in an outstanding 139-ball knock that overshadowed the achievements of team-mate Lungi Ngidi, who had claimed 6-58 earlier in the day.
The paceman became the fastest South African to 50 ODI wickets on his way to career-best figures in the format, David Warner the first of his victims after smashing 35 during an opening stand of 50 with Aaron Finch.
Ngidi also struck twice in successive balls during the 13th over, removing Steve Smith (13) and Marnus Labuschagne, the latter cutting his first delivery to Malan at point.
Captain Finch and D'Arcy Short both made 69 - the latter posting his maiden ODI half-century - while Mitchell Marsh (36) carried his team to a promising position heading into the closing stages.
Yet from 238-5 with six overs to go, Australia lost their way. Ngidi returned to get rid of Ashton Agar, Alex Carey and Pat Cummins, while Anrich Nortje trapped Starc lbw off the last ball of the innings.
The tourists will hope to avoid a 3-0 series loss when they round out their limited-overs tour with the third and final one-dayer, which takes place on Saturday in Potchefstroom.