Chasing an improbable 376 for victory, the South Africans, who were 62 for one overnight, folded up for 272 just 10 balls before the scheduled close of play on the final day.

However Proteas clinched the winner's trophy after triumphs in the first two matches in Perth and Melbourne. Smith won the man of the series award for his aggregate of 326 runs and "exceptional leadership" in the series.

After Australian skipper Ricky Ponting set up an exciting finale with his bold declaration on the fourth day, it was left to the South Africans to make a match of it but they collapsed to 171 for five by the 71st over leaving them with no choice but to fight for a draw.

Hashim Amla (59) and A B de Villiers (56) were the top-scorers for the Proteas but it was Smith who stole the show by coming out to bat after the fall of the ninth wicket.

Even with a broken right-hand finger, which has forced him to give the upcoming one-day series a miss, Smith decided to take the field after Dale Steyn's (28) dismissal in the 108th over.

The left-hander entered the ground to a rousing reception, with the SCG standing up to applaud the visiting skipper for his gritty decision.

Smith batted in discomfort for his three runs but managed to hold on for nearly seven overs with Makhaya Ntini (23 not out) at the other end.

The duo were just 10 balls away from saving the match for their team but Mitchell Johnson finally ended Australia's agonising wait for a consolation win by ripping through Smith's defences in the 114th over.

But there was plenty of drama before the Aussies could actually celebrate the consolation win with Ntini riding his luck to frustrate the world champions. The Proteas pace spearhead was dropped twice after surviving a close run out attempt.

Andrew McDonald got an easy caught and bowled chance in the 108th over but perhaps not expecting it the debutant all-rounder could not hold on, much to the dismay of his under-fire skipper Ponting.

Ntini added to the Aussie agony in the next over after struggling opener Matthew Hayden put down an even easier chance.

Pacer Doug Bollinger, another debutant, watched in horror as Hayden, despite getting two hands to the edge that had flied off Ntini's blade, spilled a regulation catch in the slips.

Earlier, Amla and de Villiers were the only South African batsmen to hold their own on a precarious SCG track. While Amla's 59-run knock came off 112 balls studded with nine fours, de Villiers took 144 deliveries to reach his 56 that had eight fours.

Peter Sidlle returned the best figures among the Aussie batsmen, scalping three wickets for 54 runs in his 27 overs, 12 of which were maiden.