The scoreboard will always shine brightly with four tries but the Wallabies' win in the second Rugby World Cup semifinal will long be remembered for their unwavering defence. Surely, however, they realise they can't put themselves under similar defensive pressure in six days' time.

The Aussies secured themselves that showdown with New Zealand, the first tournament decider between the two nations, with a tackling effort similar to the one they produced against Wales -- only this time they were forced to deal with far more creativity in the form of Argentina.

The South Americans must have wondered just what they had to do to cross the stripe as time and time again they managed to open the Aussies up; but, with the regularity of the "Ole Ole Ole, Pumas, Pumas" sung by their fans about Twickenham, they were unable to find a way to score the try they so desperately needed to close the gap.

The Wallabies scored in just the second minute and thy were clear on the scoreboard thereafter; the Pumas closed within seven points midway through the second half but they could never get any closer.

While the Wallabies were forced to endure long periods of defence, evidenced by their 142 tackles to the Pumas' 95, they also produced a couple of sublime moments in attack -- with Adam Ashley-Cooper the beneficiary on both occasions.

After lock Rob Simmons, the most unlikely source of an intercept, picked off an inside ball from Nicolas Sanchez and lumbered 20 metres to touch down, Wallabies fly-half Bernard Foley then produced a cut-out ball of such beauty that Ashley-Cooper didn't even have to break stride to swallow. A third try before the break, Ashley-Cooper's second a reward for a more patient build-up, also eventuated from a final cut-out pass with veteran Matt Giteau this time the provider.

Australia's Adam Ashley-Cooper dives to score his second try © Getty Images

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But the Wallabies would do little more attacking for the remaining 49 minutes.

The Pumas, an attacking basketcase just a few months ago, began to open up the two-time champions at will with fly-half Nicolas Sanchez so often their first point of inspiration; the diminutive playmaker regularly catching out tiring Wallabies forwards with a left or right-foot step.

Just before the break, it looked for all certainty the South Americans would score but desperate cover tackles from Foley and Will Genia forced a wayward final pass and the five points went begging. It set the tone for the second half. No matter how many times they cut through, or how many phases they were able to build, the Pumas were unable to best the gold wall.

Australia's David Pocock celebrates victory © MARTIN BUREAU/AFP/Getty Images

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Under an injury cloud throughout the week, No.8 David Pocock was heroic. While he wasn't able to provide the breakdown brilliance for which he is known, 13 carries and just as many tackles show the scope of his contribution. Atop the tackle chart two beyond Pocock was fellow back-row warrior Scott Fardy, while Michael Hooper, as usual, threw himself about with abandon.

It was quite an effort from the trio, and one they'll need to repeat again next week.

Another effort like the one Drew Mitchell produced down the left-hand touchline in the 71st minute won't go astray either. In a throwback to his breathtaking solo try in the European Champions final at Twickenham, Mitchell hit a flat cut-out pass from replacement No.9 Nick Phipps to charge down the left touchline, step inside what seemed like a dozen Pumas, before finding best mate Ashley-Cooper with a bounce pass.

It killed off the Pumas once and for all. The semi-final result was in the books.

But the job is not done yet as a final challenge against rugby's ultimate challenge, the All Blacks, now awaits.

The two sides split their Bledisloe encounters earlier this year with Wallabies coach Michael Cheika coming under huge criticism for his decision to make six changes following Australia's win in Sydney.

They were promptly whipped 41-13 in Auckland.

Whether Cheika was keeping a few cards up his sleeve in the hope he would meet New Zealand for a far bigger prize a few months later only the coach himself will know.

One thing is perfectly clear to all and sundry, however: the All Blacks will have little trouble in cruising to a third Webb Ellis crown if the Wallabies concede as many linebreaks as they did against the Pumas; another night of scrambling just won't cut it.