Australia six wickets from glory

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Australia will assume the unofficial crown of the world's best Test team some time later today in Cape Town unless South Africa can summon the sort of acumen and resistance that has noticeably eluded them for much of the current series.

Indeed, it will require the spirit – and the same central characters – who delivered the Proteas a famous draw from a remarkably similar last-day position in Adelaide 18 months ago – to prevent an overnight total of 4-71 becoming a hefty defeat.

With more fine weather forecast for Newlands and with their top four batsmen already accounted for – and a victory target of 510 as unthinkable as it is unreachable – South Africa must somehow bat an entire day to deny Australia a 2-1 series win against the team currently ranked No.1 in the world.

While that ranking won't change regardless of how day five pans out, so emphatic has been Australia's performances in the first and third Tests – interspersed by a thumping win by the home team in the second game – they can feel entitled to claim the mantle on an informal basis.

And so completely have David Warner and Michael Clarke outbatted them, and new-ball pair Mitchell Johnson and Ryan Harris outbowled them in this match, only the most myopically biased South African fan could argue that verdict.

While it was another spirit-sapping century from Warner that set up Australia's victory platform in the second innings, the three strikes that Harris and Johnson landed in a decisive six-over spell prior to tea put the outcome all-but beyond question.

Harris claimed his 100th wicket in his 24th Test when he had opener Alviro Petersen lbw in the third over, then Johnson stepped up to ruin Graeme Smith's innings and scatter Dean Elgar's stumps in the space of 12 balls to leave South Africa in tatters before they had a chance to become defiant.

Clarke answered the second-most talked about question that hung over the fourth day's play at around 2.30pm when he declared Australia's second innings – his second declaration of the Test – shut at 5-303.

That left the world's top-ranked team a touch over four sessions and roughly 140 overs to survive – the target was so ridiculously large they were never going to consider chasing it – to finish the series on level-pegging.

The most aired query was settled 16 minutes into South Africa's reply when those who wondered how Smith would perform in his final innings were handed the inevitable answer given recent history – 'out for three, caught at short leg fending off an angry ball from Johnson'.

It prematurely ended a forgettable day and a personally disappointing series for the celebrated South Africa captain, whose hopes of ending his career with his nation's first series win over Australia on home soil since readmission effectively ended at the coin toss.

Or, if not then when the Australians took first use of the pitch and put the game beyond reach by batting more than two days, then the moment that his fast bowling spearhead Dale Steyn strained a hamstring and was reduced to little more than an onlooker.

The man who took the game away from Smith and his team on day one returned to do it again, in even more emphatic fashion if that's imaginable, on day four.

As is his way, Warner had broadcast his intentions the previous evening when he used the six overs prior to stumps not to cautiously ensure his wicket remained intact but to inflict one further psychological blow on the already-reeling South Africans by plundering 25 runs from 17 balls.

It didn't take him long to warm to that theme this morning, as he took to the flagging Proteas' bowlers with a gusto and a menace that suggested he had at least one more point to prove before series' end.

He charged to 50 as he and Chris Rogers fashioned another century opening stand before Rogers fell in the only way that seemed likely on a pitch that wasn't playing quite as many tricks as many had feared, and against an attack that was by now largely going through the motions.

That was by dint of a run-out, when Steyn snared a wicket in the only way that seemed available to him courtesy of a direct hit from close to the boundary.

When he did finally appear at the bowling crease, clearly hobbled but trying to achieve some meaningful pace, Warner stared him down and dismissively slapped him back over his head for six.

But the dismissal of Rogers achieved what the South African attack – rendered even more impotent by the ineffectiveness of world No.2 Vernon Philander who has appeared out of sorts or bereft of interest in this campaign – could not and stemmed the run rate.

With Alex Doolan at the crease, the Australians struggled to find the boundaries that until that stage had been plentiful and even Warner – currently enjoying the form of his life – found runs frustratingly difficult to conjure.

It was as if word had been sent out with Doolan to ease off the morning's frenetic pace so the declaration could be delayed until the pitch deteriorated further under heavy traffic and bright sun.

Or maybe it was just the Tasmanian's becalming influence at the crease, for no sooner did he depart to a miscued hook shot after lunch than the pedal was pressed once more, albeit with even greater urgency and effectiveness than before.

The elevation of Shane Watson to No.4 underscored the dressing room's message, and he slipped quickly into his required destroyer's role by belting 25 from 17 balls, including a full-toss from part-time spinner Dean Elgar that cleared the perimeter fence, landed in the adjoining Newlands railway station and was last seen aboard the 13:36 to Simon's Town.

But even Watson's deployment as pinch-hitter paled alongside Warner's reinvigorated assault that carried him to the eighth century of his reconstructed Test career, his fifth since returning to the team last November, his third of this series and his second of this Test.

That final achievement has been matched just once at Cape Town, by the widely-proclaimed 'King' of South African cricket, recently-retired all-rounder Jacques Kallis.

Warner now assumes his own regal place in local lore having plundered 543 runs at a Bradman-esque average of more than 90 in a series that has been defined as much by his calculatedly explosive bating as it has been by compelling bowling spells from Johnson, Steyn and Morne Morkel.

Many thought Clarke might call a close to his team's innings midway through the afternoon session when Watson was dismissed and the lead stood beyond 450.

The captain might have wished that was the case when he holed out to the first ball he faced in search for further quick runs, thereby becoming the first player since England's Dennis Amiss in 1973 to score more than 150 and a golden duck in the same Test.

Any rumblings about the delayed timing of the declaration were soothed by the opening spells of Harris and Johnson that reduced the home team to 3-15 in the six overs prior to tea and Dean Elgar's stumps into an exaggerated game of pick-up sticks.

At that stage, only Amla, De Villiers and Du Plessis stood between Australia and victory some time later today.

By stumps, that resistance had been reduced to the latter pair after James Pattinson justified his call-up in place of Peter Siddle by trapping Amla in front via the magic art of reverse swing.

Third Test - day four