AS great rugby rivalries go, Australia and Argentina is still a work in progress, lacking the historical and cultural antagonism shared by the likes of New Zealand and South Africa or England and Wales.

The Wallabies and Pumas only played each other for the first time in 1979, and have met just 24 times in total, with the outcome mostly predictable, the Australians winning 18 times, Argentina five with one match drawn.

But now the stakes have been raised like never before with the teams preparing to square off in Sunday's World Cup semi-final at Twickenham. What might have been a budding rivalry has suddenly escalated into an epic dogfight.

"We're not surprised at all about their position here," Australia coach Michael Cheika said. "So we've been preparing accordingly."

No longer pushovers, Argentina made the semi-finals in 2007 and have emerged as a genuine global force since joining the Rugby Championship in 2012, regularly pitting themselves against the southern hemisphere giants.

The Wallabies go into Sunday's match as slight favourites but Cheika is under no illusions about the challenge facing his team, which has been left battered and bruised from three successive matches against England, Wales and Scotland.

Those matches took their toll and Australia were lucky to get past the Scots, needing a last-minute penalty to secure a 35-34 win, and have shown real signs of vulnerability.

But they received a major boost yesterday when two of their most influential players, the No.8 David Pocock and the full-back Israel Folau, were cleared to return after missing the quarter-final though injury.

Australia's free-flowing, high-tempo game relies heavily on their ability to hold their own in the scrum and lay a platform for the playmaker Bernard Foley to organise the backline.

A nerveless goal-kicker, Foley's general game has fluctuated during the tournament, adding an air of unpredictability to how Australia will perform tomorrow.

Against England, the Wallabies were in full flight, showing off their wide array of attacking skills, while against Wales, they defended magnificently.

They scored five tries in the quarter-final but silly mistakes allowed Scotland the chance to steal victory at the death before Australia regained their composure in the nick of time.

"We're happy to be in this position, no doubt," the Wallabies flanker Michael Hooper said. "But we're not looking up saying thank you. We want to go further, we want to do more."

On past performances, Australia hold all the aces. The Wallabies have never lost a World Cup match in Britain or Ireland, winning the title in 1991 and 1999.

They have won 10 of their l1 matches against Argentina over the last 15 years, including a comprehensive 34-9 drubbing at their most recent meeting three months ago.

But the Pumas are a team who have hit their best form at the perfect time. Their lone win over Australia since 2000 was in 2014 and they have enjoyed a relatively smooth run to the semis.

Despite losing their opening pool match to the All Blacks, they have not put a foot wrong since, storming into the last four with an impressive 43-20 win over Ireland in Cardiff.

In keeping with their Latin traditions, Argentina's game is still based around a big, powerful scrum and an unerring kicker, with fly-half Nicolas Sanchez slotting over nine from 10 against the Irish.

But the benefits of playing in the Rugby Championship have added a new attacking edge to the Pumas who are now as adept as anyone at running the ball.

Against the Irish they piled on four tries and have vowed to continue their attacking mindset against the Australians.

Argentina captain Agustin Creevy rubbished any suggestion the Pumas had achieved their goal by reaching the last four for the second time.

"We still haven't reached our objective. We're not going to relax, this team is not going to stay with what they've got so far," he said defiantly.