|Ruan Pienaar of South Africa races through the Australian defence [GALLO/GETTY]
Winger Jongi Nokwe became the first player to score four tries in a Tri-Nations match as South Africa routed Australia 53-8.
Nokwe's quartet were complemented by four more from lock Andries Bekker, centre Adrian Jacobs, replacement flyhalf Ruan Pienaar and Odwa Ndungane.
Replacement fullback Percy Montgomery added two conversions, and flyhalf Butch James kicked three conversions and a penalty.
The Wallabies, who had been aiming to win successive tests in South Africa for the first time in 45 years after last weekend's win in Durban, managed just one try through fullback Drew Mitchell and flyhalf Matt Giteau added a penalty.
Giteau slotted a simple 15-metre penalty five minutes into play and Australia held the lead for a further 10 minutes before Springbok fullback Conrad Jantjes released Bekker through a short gap, and the lock ranged over for the first try of the match.
The hosts struck again four minutes later when scrumhalf Fourie du Preez took a quick tap free-kick inside the visitors' 22 and passed to centre Jean de Villiers who found Nokwe for the winger's first try.
The speedster went over in the corner for his second following a five-metre scrum to make it 17-3.
James added a penalty before Nokwe completed his hat-trick, and secured the
bonus point, with four minutes remaining in the first half.
Capitalising on errors
Wallabies hooker Tatafu Polota-Nau's inaccuracy at a lineout on his 22-metre line cost the visitors when centre Jean de Villiers latched onto a loose ball, before it was worked wide for Nokwe to canter over and extend South Africa's lead to 27-3 at the break.
A strong scrumming effort laid the platform for the first try after the break.
De Villiers again straightened the line before flicking a pass off his outside shoulder to Jacobs in close support.
The outside centre burst through the line before weaving around the last defender to score.
Another powerful scrum by the home team again unleashed the Springbok backs as James took a well-executed pass on the loop to send Jantjes surging over the gain line, the fullback toed the ball ahead and Ndungane gathered and passed inside to Nokwe to score.
A string of substitutions punctuated play before Mitchell sprinted over for a consolation try at the end of the third quarter.
The home team replied with a brace of tries in the final 10 minutes when Pienaar jinked through the Australian line and Ndungane dived over in the final minute.
South Africa end the tournament in third place with 10 points, while Australia remain in second with 13 points, one point behind New Zealand.
The Wallabies now return home to face New Zealand in Brisbane on September 13 for the series-decider.
South Africa fullback Percy Montgomery announced his retirement from international rugby after the Springboks' victory.
"Not many players get to choose when they want to leave test rugby, and I think that's what makes it so special for me because I know that at test level it's time to go," the country's most capped player and leading points-scorer said.
"I've had many memorable moments in the Springbok jersey and some very testing ones as well, but I'd never exchange one moment of either the highs or lows.
"It's been a privilege to play for my country and to play in some of the best teams the world has seen," added the player, who earned his 102nd cap against Australia.