South Africa beat Australia 28-8 to set up a winner-takes-all Championship showdown against New Zealand.
Zane Kirchner, Willie le Roux and Adriaan Strauss scored the tries at Newlands in Cape Town as the Springboks recorded their fourth win from five.
South Africa fly-half Morne Steyn, who was winning his 50th cap, added two conversions and three penalties.
Australia suffered a record 38-12 home defeat to South Africa in Brisbane earlier this month and were overwhelmed in the opening quarter.
Strauss crashed over after a couple of phases of possession in the eighth minute and just two minutes later Kirchner crossed after receiving a great pass from Jean de Villiers.
Steyn added the extras on both occasions and that was sandwiched by two penalties to give the hosts a 20-3 lead inside 18 minutes.
Christian Leali'ifano's sixth minute penalty, which had given the Wallabies an early lead, was now a distant memory.
There was no further scoring until nine minutes from time when winger le Roux squeezed over in the corner which was a disappointment for the home fans who were seeking the bonus point that comes from scoring four tries.
The game became increasingly bad-tempered and four yellow cards were handed out by French referee Jerome Garcès.
Home players Flip van der Merwe and Duane Vermeulen and Australia's Michael Hooper and Sitaleki Timani were all sent to the sin-bin.
A win is a win, but can't help feeling deflated - both Boks' 2nd-half and performance of the ref http://t.co/wUZlNU0Zre— rugby365 (@rugby365com) September 28, 2013
Replacement Chris Feauai-Sautia scored a consolation for Australia three minutes from time but they just have their narrow 14-13 win over Argentina in Perth in the win column.
South Africa now top the table on 18 points but New Zealand, on the same total with a game in hand, are expected to win in Argentina later tonight.
The two top-of-the table sides meet in Johannesburg next Saturday.