The Wallabies condemned South Africa to a third straight Tri-Nations defeat with a convincing 30-13 win in Brisbane yesterday.

The world champions' hopes of retaining the southern hemisphere championship suffered another heavy blow as they were outplayed in a frenetic Test match punctuated by three yellow cards.

Australia's winning margin would have been greater but for haphazard finishing which cost them the chance of landing a four-try bonus point to keep in touch with series leaders New Zealand, who they face in Melbourne next week.

For all the Wallabies' dominance, they had only tries from Drew Mitchell and Will Genia to show for their efforts, while the Springboks also crossed the line twice, their first tries in five matches at Lang Park.

The key difference between the sides was in goal-kicking, with Matt Giteau landing five penalties and James O'Connor a penalty and a conversion for Australia.

Australia are now unbeaten against South Africa in seven Tests at Lang Park - the Springboks last won in Brisbane 39 years ago at the Exhibition Ground across town.

Irish referee George Clancy pulled out the yellow card three times, sin-binning Springboks Jaque Fourie and BJ Botha and Wallaby Quade Cooper.

Australia's finishing lacked composure at times, with breaks by Rocky Elsom and Genia going unrewarded, and the home side needed Giteau to kick them into a lead.

Australia continued to rip through the South African defence after the break but poor finishing let them down again and it took penalties from Giteau and O'Connor to pull them into a 23-3 lead.

The South Africans refused to give in and Fourie scored after a John Smit pass in the 62nd minute to bring the scores to 23-8.

The Springboks scored their second try eight minutes from time through prop Gurthro Steenkamp but scrum-half Ruan Pienaar failed to convert.

The Wallabies wrapped it up with scrum-half Genia scampering over five minutes from the end for a try converted by O'Connor.