De Villiers leads South African defiance against Australia
South Africa's Kyle Abbott (centre) is surrounded by Australian fielders on the fifth and final day of the third Test at Newlands in Cape Town, on March 5, 2014 - by Luigi Bennett
South Africa were 122 for five at lunch after batting for 80 overs, although a new ball was due immediately after the interval and a minimum of 59 overs remained in the match.
A target of 511 to win had long been abandoned by South Africa, but they are trying to save a series which is tied at 1-1.
James Pattinson took the only wicket of the morning, the fast bowler breaking a stubborn fifth-wicket partnership between De Villiers and nightwatchman Kyle Abbott.
The duo defied Australia's bowlers for just over an hour and a half during an extended morning's play before Abbott, who batted for 116 minutes and faced 89 balls in scoring seven runs, did not play a shot to a ball which cut back and clipped the top of his off stump.
The home side's hopes rested with De Villiers and Faf du Plessis, two of the key figures when South Africa fought out a draw from a similar position in Adelaide in November 2012.
De Villiers, normally a free-scoring batsman, started his innings after tea on the fourth day, and by lunch on day five he had faced 214 balls and scored only 39 runs.
It was an effort reminiscent of De Villiers' innings in Adelaide when he batted for more than four hours and faced 220 balls in scoring 33.
On that occasion, Du Plessis, making his debut, saved the match with a marathon innings of 110 not out. He was on 14 not out on Wednesday.