Du Preez scored South Africa's opening try of the match
South Africa 24 (3)
Tries: Du Preez, Paulse
Pens: Pretorius 3
Drop goal: Pretorius
Australia 16 (3)
Pens: Mortlock 3
South Africa ended this year's Tri-Nations on a high with a scrappy victory over Australia.
The Springboks still finished bottom of the table, but finished the tournament with two straight wins.
A low-key first-half ended 3-3 thanks to kicks from Stirling Mortlock and Andre Pretorius.
Australia took the lead through Stephen Larkham's try, but scores from Fourie du Preez and winger Breyton Paulse sealed South Africa's win.
The defeat continued Australia's dismal away record in the Tri-Nations, with their last win on the road coming back in 2001.
Meanwhile, South Africa showed they had learned the lessons of their 49-0 thrashing by the Wallabies in July as their resolute defence proved decisive.
The match was marred by aimless kicking from hand, and the careless coughing up of possession at the breakdown with both sides equally guilty.
Larkham dives over for Australia's only try
And the dour first half also saw four penalty attempts go astray in a poor advert for the Tri-Nations.
The match opened up after the break, although it was Pretorius' second penalty which provided the first points of the second half.
Larkham applied the finishing touch to the first genuinely flowing move of the match when he collected a good pass from number eight Wycliff Paul after Australia made the most of turnover ball.
Pretorius added a third penalty and a 40m drop-goal though for the Springboks, and Du Preez powered his way over after a close range tap penalty as the home side took control.
Mortlock punished South Africa indiscipline with two penalties to ensure a nervy close to the match, but Paulse's try - after good build-up work from Victor Matfield and debutant JP Pietersen - completed the scoring.
South Africa coach Jake White:
"When you consider where this team was a month ago, to win two consecutive games, and today - against the most-capped backline in the history of the game - is amazing.
"Most sides would have thrown in the towel in such a difficult time. When you get into a downward spiral like that, usually the players fall apart and things go pear-shaped.
"But everyone put their weight behind the effort and the team has learnt a lot of things these last two weeks: a huge amount of positives have come out of it."
Australia coach John Connolly:
"We created enough opportunities, but we're really disappointed with our execution.
"We trained so well but we never took it on to the field in certain areas.
"We just didn't gel, we became anxious and we probably became a bit flat in the backs.
South Africa: JP Pietersen; Ndungane, Fourie, De Villiers, Olivier; Pretorius, Du Preez; Os du Randt, Smit (capt), BJ Botha; Muller, Matfield; Spies, AJ Venter, Wannenburg.
Replacements: Ralepelle, Sephaka, Van den Berg, Cronje, Pienaar, James, Paulse.
Australia: Latham; Rathbone, Mortlock, Giteau, Shepherd; Larkham, Gregan (capt); Robinson, Paul, Blake; Sharpe, Vickerman; Elsom, Waugh, Palu
Replacements: McIsaac, Baxter, Chisholm, Smith, Sheehan, Gerrard, Staniforth.