Australia have a little over four sessions to bowl South Africa out and claim victory in their three-Test series after declaring with a second-innings lead of 510 runs in Cape Town.
The tourists were led by David Warner, whose second century of the match was a knock of 145 from just 156 balls.
Chris Rogers (39), Alex Doolan (37), Shane Watson (25) and Steve Smith (39*) also contributed decent scores as Australia raced to a second-innings total of 303-5 before they were called in.
Captain Michael Clarke top-scored in the first innings with an unbeaten knock of 161, but he couldn't replicate that as he was out for a golden duck off the bowling of Kyle Abbott, who led the Proteas' bowling with three wickets.
South Africa now have to either score 511 runs to win the third and final Test or more likely bat out until tomorrrow evening for a draw.
Alviro Peterson and Graeme Smith, who is batting in his final international innings after announcing his retirement, are currently at the crease.
