South Africa will enter the final day of the third Test against Australia needing a further 314 runs to pull off an improbable win and secure a 3-0 series whitewash.
Set an imposing victory target of 376 from a minimum 116 overs, the Proteas were 62 for one at stumps on day four.
Stand-in skipper Neil McKenzie and Hashim Amla, who are unbeaten on 25 and 30 respectively, will resume the fight for a historic last-day win - with at least 90 overs to be bowled.
Previous fourth-innings run-chases at the SCG suggest victory may be beyond the Proteas on a wearing wicket - despite their epic pursuit of 414 to win the first Test in Perth.
Australia's fourth-innings total of 288 for two in 2006 season against South Africa is the highest winning total in a Sydney Test.
The tourists' task is made more difficult by the absence of skipper Graeme Smith, who is nursing a broken finger and is highly unlikely to take any further part in proceedings.
After Australia declared their seconds innings on 257 for four, Doug Bollinger made the early breakthrough, claiming his first Test wicket when makeshift opener Morne Morkel chipped a catch to Mitchell Johnson at mid-on.
Amla survived a close call on five, edging Peter Siddle past a diving Brad Haddin, before shepherding South Africa to the close without further alarm.
Australia had resumed on 33 without loss with Matthew Hayden and Simon Katich at the crease.
Hayden played on to Morkel for 39 in what could be his last Test innings, and was given a rousing send-off by an appreciative crowd.
Ricky Ponting almost collected a king pair, leaving the first ball he faced only for it to catch the inside edge of his bat, narrowly miss the stumps and fly to the boundary.
The skipper's innings then flourished as he raced to a half-century at almost a run a ball, and it came as something of a shock when he chopped on for 53 attempting to cut Morkel.
There was also much surprise when Katich was adjudged lbw for 61 to Dale Steyn, with only wicketkeeper Mark Boucher interested in an appeal.
However, Michael Clarke and Mike Hussey shared a fourth-wicket partnership of 76 that helped put Australia in the box seat to record their first win of the series.
Ponting closed his side's innings after Clarke was caught in the deep for 41 chasing quick runs. Hussey finished 45 not out.
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