World Cup champion South Africa went into the match unbeaten in the Tri-Nations and needing only a draw to clinch the title but never got in front, extending a losing streak in Brisbane that dates back to 1971.

The Australians had three tries disallowed before Adam Ashley-Cooper crossed in the 63rd minute to break open the match, giving the hosts a 16-6 lead.

Teenage fullback James O'Connor sealed it in the 76th with an opportunist try, picking up at the base of the Springboks ruck on the quarterline and racing untouched to score.

Wallabies flyhalf Matt Giteau kicked two penalties, a dropped goal and a conversion, while his opposite Morne Steyn landed a penalty and a dropped goal in the first half.

The Springboks can clinch the title next week with a draw or better against New Zealand at Hamilton. The All Blacks can still win the competition but need two bonus-point victories in the home matches against South Africa and Australia to defend the title.

"They had to work hard for it. We had three disallowed, but the guys kept coming _ that was the most important thing," Wallabies coach Robbie Deans said. "They got what they deserved.

"I'm proud of the way the boys stuck at it, kept working. the result came at the end. We look forward to pushing on from here."

Australia led 9-6 at the break, hanging onto the slender lead when a Springboks' try was disallowed right on half time.

Giteau kicked penalties in the 6th and 27th minutes before Steyn replied with a penalty goal in the 29th.

The Australians were intent on spreading the ball from all parts of the field and it got them close twice in three minutes, only to be denied both times by Bryan Habana's try-saving tackles.

Habana pushed opposite winger Lachie Turner into the corner flag in the 17th minute with a late, desperate shove.

In the 19th, he pulled down Giteau after the Wallabies flyhalf sliced through the Springboks midfield near the quarterline and away from his unmarked support.

The Springboks got closest to scoring when Jean de Villiers burst through a gap outside Giteau _ exposing a defensive lapse in that space for the second time in the half.

He passed infield to center partner Jaque Fourie, who was dragged down two meters out and then stripped of possession by O'Connor.

Steyn and Giteau traded dropped goals to make it 9-6. The Springboks crossed on the stroke of half time, but Fourie du Preez' last pass to flanker Heinrich Brussow was ruled forward.

In the second half, scrumhalf Will Genia took a quick tap from 10 meters out rather than a certain three points via a goal. He crossed the line but the video referee ruled that du Preez ripped the ball away before Genia touched down.

Giteau had a try disallowed after snatching Adi Jacobs' risky pass deep inside the Springboks territory and burrowed into the right corner. The video referee ruled that he put a foot into touch in Jaque Fourie's desperate tackle.

There was no doubt about Ashley-Cooper's try. He ran onto a flat ball from Berrick Barnes on the quarterline and straight into open space to cross untouched.

Giteau converted to make it 16-6 and missed a long-range penalty goal before O'Connor sealed it, running 20 meters unopposed to score.

Scores:

Australia 21 (Adam Ashley-Cooper, James O'Connor tries; Giteau 2 penalties, dropped goal, conversions), South Africa 6 (Morne Steyn dropped goal, penalty goal.) Halftime: 9-6.