Australia captain Ricky Ponting became only the sixth player to score a century in his 100th Test as he and Adam Gilchrist frustrated South Africa.
Australia were all out for 359 with Ponting making 120 and Gilchrist 86 on the third day of the final Test in Sydney, a deficit of 92 runs.
At the close South Africa were 4-1 in their second innings after Brett Lee trapped AB de Villiers lbw for three.
The hosts weathered the morning session as they recovered from 54-3.
The tourists might have had a much bigger lead had it not been for Ponting and Gilchrist who tore into the visiting bowlers with a ferocity that belied Australia's shaky position
Ponting fell lbw to Jacques Kallis after recording his 27th Test century and Andre Nel then removed Andrew Symonds (12) and Shane Warne (0) in successive balls.
Ponting is the only Australian to record a century in his 100th Test, and joined Colin Cowdrey, Javed Miandad, Gordon Greenidge, Alec Stewart and Inzamam-ul-Haq as the only players to achieve the feat.
But he had to survive a loud lbw appeal on 95 off Charl Langeveldt where replays showed the ball would have gone on to hit the middle and leg stumps.
Earlier in his innings, Ponting passed Mark Waugh into third on Australia's all-time list of Test run scorers as he smashed 12 boundaries and a six in his innings.
But after the mini collapse following his dismissal, Australia were struggling on 226-7 at tea, still 26 short of avoiding the follow-on.
However Gilchrist, who had been struggling since the Ashes, rediscovered his form to keep the tail wagging, belting 10 fours and two sixes off 109 balls in 156 minutes.
The knock and Australia's innings ended when he gloved Nel's short ball to wicket-keeper Mark Boucher.
Nel was the pick of the South African bowlers, finishing with 4-81, with Jacques Kallis and Charl Langeveldt each claiming two.
South Africa's second innings did not start well as Brett Lee gave Australia a huge fillip just before the close, trapping AB de Villiers lbw for three.