Cape Town, South Africa: Australia is likely to seek quick runs and then make an early declaration of its second innings on day four in Cape Town as it seeks to capitalise on its dominance and become the first team in five years to beat South Africa in a series.
Strike-bowlers Ryan Harris (3-63) and Mitch Johnson (4-42) both thrived as the home team was dismissed for 287, well short of the 7-494 that Australia declared at before the start of day three at Newlands.
The visitors then survived what could have been a tricky six-over period at the end of the day, although there was - typically - no sign of any nerves in David Warner's batting as he thumped four boundaries from the 17 deliveries he faced.
Australia finished day three at 0-27, leading by 234, with Warner on 25 and Chris Rogers on 1.
At one stage it looked as if the Proteas could have been dismissed well within two sessions. The scalps of the talismatic A.B. de Villiers (14) and J.P. Duminy (4) within the first seven overs after lunch left them reeling at 6-146.
They were then indebted to a 95-run partnership compiled from almost 40 overs from Faf du Plessis (67) and Vernon Philander (37 not out) to prevent their tail being exposed before the half-way mark of the day.
The combination of Johnson and the sure hands of Warner to a low chance at gully that removed du Plessis, who had been given three lives - one of them a seemingly straightforward stumping by Brad Haddin - by Australia in the field.
The lusty hitting of Dale Steyn (28 off 27) took South Africa close to the mark of 295 it needed to prevent Australia enforcing the follow-on. That it fell eight runs' short was irrelevant as Clarke chose to bat again.
Given Clarke had declined the other two follow-on opportunities during his captaincy, in January 2012 when it held a 332-run lead over India at the Adelaide Oval and in December at the same venue when England's deficit was 398, it was not surprising he shunned the chance to make do with a 207-run lead after his team had been in the field for 82.5 overs.
The faith Australia selectors maintained in Harris, whose series record going into the match was three wickets at 74.33, was emphatically vindicated as the previously struggling paceman claimed two crucial scalps in the first session.
Harris continued the horror series of South Africa captain Graeme Smith by removing him for 5, leaving him a miserable 42 runs at 8.4, and then just before the break producing a near-unplayable delivery that swung in sharply and clattered the stumps of the previously imperious Hashim Amla.
While logic said South Africa, having to respond to Australia's first-innings total of 7-494 declared, would be primarily intent on survival a run-a-ball half-century from Alviro Petersen indicated it was not resigned to a draw being its best result from the last three days of this Test at Newlands.
The confidence demonstrated by the South African batsmen, particularly the always-elegant Amla, suggested home team seamer Kyle Abbott's prediction the previous evening that day three would feature the best batting conditions for the match was a legitimate one. But even helpful pitch conditions cannot save some batsmen from excellent bowling and wicketkeeping.
The early boundary from Proteas captain Smith proved to be his only meaningful contribution as he managed only one more run before edging behind off Harris, who after relentlessly angling the ball across the left-hander eventually tempted him into a nick.
Haddin has yet to replicate his batting heroics of the home Ashes series but his proficiency with his primary skill, assured glovework behind the stumps, gave Australia the scalp of Elgar for 11.
The left-hander tried to defend a delivery off the back foot to the lively James Pattinson but got an inside-edge, from which Haddin hurled himself to his right at full stretch to claim a brilliant one-handed catch.
The suggestion that Pattinson was a high-risk, high-reward selection in place of Peter Siddle was given credence when he conceded 18 runs to Petersen from the first over after drinks, to leave him with first-spell figures of 1-32 from four overs. He did, however, improve in later spells.
Right-hander Petersen batted with more authority than he did in Centurion to swat his way to a half-century off just 50 balls, beating his previous Test record of 55 balls.
While he stoically refused to flinch after being struck on the upper arm by a 149.7km/h bouncer from Mitch Johnson shortly after reaching his milestone he lasted only three more balls against Australia's hostile left-armer, tickling him down leg-side to Haddin.
Australia was already the victor of the session, despite South Africa's healthy run-rate, at that stage, but that status was entrenched by the scalp of Amla for 38, after Harris brilliantly hooped a delivery, seemingly with reverse-swing, that began well outside the South African's off-stump through his defences.
With Amla gone the Proteas were seemingly dependent on a team-best innings from de Villiers to mount a recovery, yet they had to look beyond that when in the fourth over after lunch he attempted to drive a ball angled across him from Johnson and got a thick edge to second slip to depart for 14. His replacement Duminy made only four before he became Harris' third victim.
It was at this stage that du Plessis filled the void left by de Villiers, with handy support from Philander - and some rare lapses by Australia's fielders.
The first two spurned chances involving du Plessis came when he was on 30, both off the bowling of Nathan Lyon. For the first the right-hander advanced to the off-spinner and missed, but was saved by Haddin's inability to clasp the ball with the batsman well out of his crease.
For the second du Plessis flicked a very difficult chance to Alex Doolan at short-leg which the Australian was barely able to get his hands up in time for.
Du Plessis' third life came in the second-last over before the break, on 35, when he leg-glanced Harris. The one-handed chance that Haddin spilled diving to his left was difficult, but not as difficult as the one he athletically snared off Elgar earlier.
After the departure of du Plessis to end the 74th over Philander effectively retreated, successfully preserving his wicket but scoring only seven runs from the last 33 balls he faced, the same number scored by Morne Morkel from the nine balls he faced.
While Steyn, in the middle for the first time since he limped off with the hamstring injury mid-way through day one, struck five boundaries, Johnson got some revenge when he struck the South African directly on the emblem of his helmet after he ducked into a bouncer.
Steyn took the field for the Proteas at the end of day three but did not bowl as Graeme Smith preserved him and ignored Philander, whose first-innings figures of 1-116 were his most expensive in Tests, and instead gave the new ball to Morkel and Abbott. Second-gamer Abbott conceded only two runs from his three overs but Morkel conceded 24 from the same period, a legacy of having to bowl to the fearless Warner.