New Zealand beat Australia to move top of the Rugby Championship table but South Africa will win the title if they defeat Argentina in their final game later on Saturday.
Quinn Tupaea scored two tries as the All Blacks claimed a bonus-point 28-14 win in a rain-soaked Perth to move four points clear of South Africa.
However, the Springbocks will claim back-to-back titles should they beat Argentina at Twickenham (14:00 BST).
Centre Tupaea, who replaced the dropped Billy Proctor, swung the game in New Zealand’s favour with two quickfire tries late in the first half.
Leroy Carter crossed in the eighth minute to give the visitors an early lead, but Australia responded with three penalties from the boot of Tane Edmed.
Tupaea’s two tries, in the 30th and 36th minutes, handed the All Blacks a 17-9 lead at half-time.
Australia’s Len Ikitau pulled a try back for the hosts midway through the second half, either side of penalties from New Zealand’s Damian McKenzie.
But George Bower came off the bench to barge over seconds after the final hooter sounded to seal the win for New Zealand and hand them the attacking bonus point.
With four points for a win, and South Africa boasting a far superior points difference than the All Blacks, the Springboks just need to beat the Pumas to take the title.
They thumped Argentina 67-30 in the reverse fixture in Durban last Saturday and with the tight turnaround in matches the Pumas have decided to play their home match in London.