|Second Test, Johannesburg (day four):|
|South Africa 266 & 339 v Australia 296 & 142-3|
Australia will begin the final day of the second Test on 142-3, chasing 310 to win the match in Johannesburg and tie the series with South Africa.
The Proteas were 229-3 overnight and AB de Villiers (73) fell early after adding 147 with Hashim Amla (105).
Dale Steyn's 41, including three sixes, ensured the tail wagged but debutant paceman Pat Cummins finished with 6-79.
The Aussie openers fell early but Usman Khawaja (65) and Ricky Ponting (54 not out) have kept them in the hunt.
However, they must break the record for the highest successful Test run chase at the New Wanderers stadium if they are to avoid losing the series.
For Ponting, especially, Monday's chase will be a chance to answer critics who have been predicting the imminent end of the 36-year-old's star-studded international career.
The former skipper, who quit the captaincy in March after Australia's World Cup exit, has not made a Test century since January 2010, and a run of low scores has led an increasing number of commentators to call for him to step down - or face the humiliation of being dropped.
Having made a duck in the first innings, Ponting took 10 balls to get off the mark and avoid a pair, and edged his way to his first Test half century since the first Ashes Test against England just under a year ago.
Vernon Philander tore into the Aussies early on, bowling Shane Watson with the second ball of the innings as the opener shouldered arms, and inducing an edge from Phillip Hughes (11) in the third over.
But Ponting added 122 for the third wicket with Khawaja, who reached his maiden Test fifty before edging spinner Imran Tahir to slip - and skipper Michael Clarke only had time to face one ball before bad light curtailed play.
Earlier, South Africa had looked likely to set the tourists a much lower target after the overnight pair Amla and De Villiers fell, as did Ashwell Prince and Mark Boucher to leave the hosts 266-7, only 236 ahead.
Steyn and Philander (23) added 48 for the seventh wicket until Cummins removed the latter and Morne Morkel with successive deliveries.
After last man Tahir survived the hat-trick ball, Steyn took the attack to Australia, hoisting Peter Siddle and Cummins for sixes in successive overs to lift the lead past 300, before becoming the last man to fall.