Cape Town, South Africa: Australia needs six final-day wickets in Cape Town to topple the world's best team on its own turf.

James Pattinson's 50th Test wicket, claimed in the last half-hour of day four against South Africa, was arguably his most consequential one as it broke the partnership between the world's top two batsmen, Hashim Amla and A.B. de Villiers, that had withstood Australia's bowlers for 30 overs.

The Proteas will begin the final day of the series-deciding Test at Newlands at 4-71, with no chance of victory. Instead, their focus will be to survive the three sessions, and up to 98 overs across them, to salvage a draw that would preserve its record of not having ceded a series home or away for five years.

De Villiers has curbed his natural aggression to the extent he scored only 16 runs from the 100 balls he faced to end day four. While nightwatchmen Kyle Abbott will be alongside him, the outcome of the match will rest heavily on how de Villiers and remaining specialist batsmen Faf du Plessis and J.P. Duminy are able to perform.

Amla looked in total control during his 109-ball innings, but like for all bar the second innings in Port Elizabeth where he scored a century, he finished it without a substantial score. Late on day four he was claimed, on 41, by a searing delivery from Pattinson that pitched well outside his off-stump but swung in late and sharply to beat his inside-edge and rap him on the pads. His resulting challenge to the leg-before decision failed.

For Pattinson, the wicket would have been a satisfying one as it involved significant reverse-swing into the right-hander, unlike his typical arc - particularly with the new ball - away from right-handers.

Amla had been chiefly responsible for preventing a collapse that threatened to develop after South Africa, faced with a victory target of 511, slumped disastrously to 3-15 after six overs of its second innings.

Those three wickets, of top-three batsmen Alviro Petersen, Graeme Smith and Dean Elgar, promptly hushed any discontent that may have arisen due to Australia waiting until the second half of day four to declare.

The first two wickets were especially significant.

Harris trapped Petersen leg-before for nine to reach his richly deserved 100-wicket milestone in Tests.

Smith was welcomed onto the ground through a guard of honour made by Australia's players, in recognition of his announcement this Test, and that innings, would be the last of his decorated career. That was where the sentimentality ended, as he nudged the third delivery he faced, from the typically hostile Mitch Johnson, directly to Alex Doolan at short-leg to depart for three.

The already strong sense of inevitably about the result of this match became even stronger when Elgar had his stumps demolished by Johnson on the verge of tea to depart for a duck. It was the left-armer's second wicket of the innings and 21st of the series.

After day three Johnson said he would ideally like five full sessions available to bowl out South Africa. His captain Michael Clarke is renowned as an attacking captain, but in this instance he waited much longer than was generally expected to call a close to his team's innings.

As Australian batted on Graeme Smith responded by progressively stacking the outfield to restrict boundaries. By the end the only South Africans not on the rope were the bowler and wicketkeeper.

Australia eventually declared 15 overs after tea at 5-303, with Steve Smith 36 not out off 20 balls and Brad Haddin 3 not out off 3 balls.

The declaration came in the over after David Warner fell, chasing quick runs, for a fine 145 off 156 balls that took his series record to 543 runs at 90.5.

In the process Warner also became only the 15th Australian to score a century in each innings of a Test, and the ninth from any country to reach 50 five times in a three-Test series. His only failure in this series came in the first innings of the first Test.

In South Africa's famous draw secured in Adelaide in November 2012 it batted for 148 overs to force a draw, with Australia unable to claim the last two wickets. In Cape Town, however, Australia effectively has two more bowling options, given Pattinson was a first-innings casualty at the Adelaide Oval and all-rounder Shane Watson was not playing.

The day began with the world's top-ranked team made to look feeble as Warner again demonstrated a level of consistency many assumed was beyond him, especially in Tests.

Australia toyed with South Africa's bowlers in the first hour of day four, with Warner and Chris Rogers pummelling the South Africa bowlers at more than a run a ball.

Australia's utter dominance was exemplified twice at the start of day four. The first was that the initial three-over spells from Vernon Philander and Dale Steyn, ranked the world's top two bowlers, reaped a combined 52 runs for Australia. The second was that the orthodox and typically dour Rogers even took to switch-hits against the off-spin of Duminy.

Australia began day four with a lead of 234 and wasted little time in extending that beyond 300. Warner was at the heart of that propulsion, reaching his half-century from just 41 balls. In doing so he became only the second Australian opener in the past 24 years - Phil Jaques was the other - to reach 50 in five consecutive innings.

The only respite for the home team came after the scalp of Rogers for 39, courtesy of some slack running and Dale Steyn's superb direct-hit from fine-leg, because it triggered the arrival of Doolan, albeit Doolan later improved after a painfully slow start to outscore Warner in their half-century partnership.

Excepting the laboured partnership between Doolan (37 off 87 balls) and Warner, 65 off 149 balls, that ended with Doolan top-edging a hook soon after lunch Australia aggressively chased quick runs throughout its innings. Shane Watson (25 off 17) and Steve Smith (36 not out off 20 balls) provided valuable support for Warner to push their team's lead beyond 500.

In that session Australia scored at just over eight runs per over. In the last session of the day the home team crawled along at 1.6 runs per over. De Villiers undoubtedly had the potential to change that, but given his team's dire circumstance his entirely resolute approach was justified. He will likely have to replicate that for another three sessions on the final day, or the bulk of them, for South Africa to memorably deny Australia a victory for the second time in 16 months.