Australia left South Africa's Tri-Nations title defence in tatters with a 30-13 win over the ill-disciplined Springboks this morning.

Flyhalf Will Genia celebrated his return from a thumb injury with a 75th-minute try to seal victory after South Africa scored two second-half tries to claw to within 10 points.

Winger Drew Mitchell scored on the stroke of halftime and Matt Giteau slotted five penalties to maintain the Springboks' winless record at Lang Park and leave their Tri-Nations campaign on the brink of collapse after three straight losses.

The Springboks did themselves few favours, having a man sin-binned at the start of each half and conceding a raft of first-half penalties to allow the Wallabies to open a 17-3 lead at the break.

The loss takes South Africa's Tri-Nations title hopes out of their hands, and they will need favourable results from Australia and New Zealand to have a chance of retaining their crown.

‘Gotta be happy with the performance. There was a lot of stuff to be proud of, particularly the defence,’ Australia coach Robbie Deans told reporters.

Jacque Fourie and Gurthro Steenkamp scored South Africa's first tries in 13 years at Lang Park after an undisciplined first half in which they managed only three points from a Morne Steyn penalty.

Steenkamp's try put South Africa within 10 points eight minutes before time and sparked hopes of an unlikely comeback, but the Wallabies absorbed fierce pressure in their 22 in a performance Deans rated their best defensive effort in his tenure as Australia coach.

As with their two previous away defeats to New Zealand, the Springboks started miserably when outside centre Fourie was sinbinned in the third minute for lifting number eight Richard Brown in a tackle.

Fourie was the third South African player sinbinned early in three consecutive matches.

‘I just couldn't believe it could happen again for the third week in a row. This can't keep happening, surely,’ lamented Springboks captain John Smit.

The Wallabies appeared determined to squander the 10-minute advantage, however, with flyhalf Quade Cooper's laser passes proving too slick for team mates on occasions.

A number of promising attacks were botched with fumbles and passes missing their targets before a ruck infringement handed Giteau the first of his four penalty goals for the half.

Mitchell finally swooped on a messy pass flung out by a prostrate Giteau five metres from the goal-line, then juggled the ball three times while pirouetting over the line to give the Wallabies their first try on the stroke of halftime.

Giteau's fifth penalty two minutes after the break put the Wallabies up 20-3, shortly before BJ Botha was sin-binned for slowing the ball down at a ruck.

South Africa mounted a belated fightback when Cooper lifted Steyn in a tackle to be sent off, and the Springboks capitalised with a try to Fourie in the 62nd minute.

The Springboks pushed hard but were repelled with some fierce tackling in the 22, but were too sapped from playing with 14 men for 20 minutes of the match to prevent Genia from crossing for the winner.

Although deflated, under-pressure coach Peter de Villiers remained defiant about the Springboks' flagging campaign.

‘The competition isn't over yet ... It doesn't mean we're not part of the competition any more,’ he said. ‘The result doesn't matter to me as such.’