Ponting slammed a career-best 164 off 105 balls on Sunday as Australia thrashed 434 for four, the highest total in One-day international history.
With the series locked at 2-2, it was an even more dominant display than Australia produced in the World Cup final at the same ground three years ago when Ponting made 140 not out in an Australian total of 359 for two. Australia went on to win by 125 runs.
Adam Gilchrist (55), Simon Katich (79) and Michael Hussey (81) made hard-hitting half-centuries as Australia took full advantage of winning the toss against a side missing star opening bowler Shaun Pollock, who suffered a back strain during the fourth match in Durban Friday.
South Africa's depleted attack started reasonably well and the total was only 13 in the fifth over when Gilchrist, on eight, was dropped by a diving Herschelle Gibbs at backward point off Makhaya Ntini.
Gilchrist went on to a sparkling half-century off 35 balls as he and Katich put on 97 for the first wicket to set the platform for Ponting's sensational innings.
Ponting reached 50 off 43 balls, his 20th One-day international century off 71 balls and 150 off 99 deliveries. His innings included nine sixes - one more than he hit in the World Cup final - and 13 fours.
Every partnership was scored at better than a run a ball. Gilchrist and Katich made their 97 off 93 balls, the same number that were needed for the second wicket stand of 119 between Katich and Ponting.
The innings went into overdrive when Ponting and Hussey hit 158 for the third wicket off 96 balls.
To add to South Africa's problems, the host team faced a fine for failing to complete their overs in time, with the innings finishing 25 minutes late.
Australia's total beat the previous world best of 398 for five by Sri Lanka against Kenya in Kandy during the 1996 World Cup.