South African captain Graeme Smith waited 77 minutes on day four before declaring on 5-270 in the second Test, setting Australia a target of 448 in Port Elizabeth.
Wayne Parnell’s groin injury means Smith is a bowler down and Robin Peterson’s omission leaves him without a frontline spinner, while 64mm rain is predicted on Monday’s final day.
But centurion Hashim Amla had little interest in hitting out and Smith wanted only half-an-hour at Australia before lunch on Sunday.
The Proteas are fully expected to square the three-Test series, given they skittled Australia for 246 in 57 overs on Saturday.
The visitors will be chasing well in excess of the 273 scored by South Africa in 1962, the highest fourth-innings total recorded at St George’s Park.
They would also need to set a new world record for a successful fourth-innings Test chase, bettering the 418 chased down by the West Indies in 2003.
Amla (127 not out) started Sunday on a nervy note by flashing at a wide ball and edging between slip and gully, but was all class from then on as he ended a lean run with a 21st Test century.
Quinton de Kock was out edging to Nathan Lyon for 34, while JP Duminy finished 18 not out.
The Proteas resumed on 4-192, adding 78 runs at roughly a run a minute.
Michael Clarke, speaking after stumps on day three, was full of belief his side could win the match.
“I don’t think we can worry too much about the weather,” he said.
“But if Parnell’s not fit to bowl, I think that will have an impact.
“If you’ve only got three fast bowlers and you’re bringing them back for their third and fourth spells, you’re giving yourself a chance.
“We didn’t do that in the first innings.”
South Africa famously survived the better part of five sessions to save the Adelaide Oval Test in 2012, when Faf du Plessis was unbeaten after almost eight hours at the crease.
Australia will need to bat longer than that, although might have some assistance with the rain.