South African coach Russell Domingo is optimistic about the final day of the Test despite Australia being in a commanding position to take the series.

Earlier, Australian captain Micheal Clarke declared on 303 for five, setting the Proteas a mammoth 511 to win. But again the top order failed and day four closed with the South Africans teetering on 71 for four.

"I think there is still hope. We're hoping AB can score the slowest 40 in the history of the game," said Domingo.

"We've still got Faf who's done it before. JP's coming off the back end of a hundred. So there's still some good batting options for us."

Smiths' charges were three wickets down after just six overs. First to fall was Alviro Petersen for nine after he was struck on the pad right in front by Ryan Harris, while Mitchell Johnson took care of Greame Smith (three) and Dean Elgar (zero) to leave the home side at 15 for three.

There was some resolute defence from Hashim Amla, who soaked up 109 balls for his 41 before James Pattinson trapped him lbw.

Nightwatchmen Kyle Abbot strolled to the crease with an ever-composed AB de Villiers at the other end when stumps were called.

Interestingly enough, the Proteas were on 77 for four on day four in the Adelaide Test match where Faf du Plessis ground out a match-saving ton.