'They would be the favourites': John Eales' assessment of wide open RWC

John Eales knows what it takes to win a Rugby World Cup but the former Wallabies skipper says who will take this year's title in France is anyone's guess.

The tournament will open with a bang on Saturday (AEST) in Paris, with hosts France taking on New Zealand to kick-off a 40-match pool phase that will be played out in nine host cities across the country.

A draw based on rankings back in 2020 means the tournament has a skewed look: three of the current top-five teams - world No.1 Ireland, South Africa and Scotland - find themselves in the same pool, with only two able to advance.

It also means only two of the game's top-four ranked teams in Ireland, New Zealand, the defending champion Springboks and France, can make the semi-finals.

Having fallen to a world ranking of ninth, Australia are on the "easy" side of the draw, facing Pool C clashes against seventh-ranked Fiji, Wales (10th), Georgia (11th) and Portugal (16th).

The top two will likely take on Argentina or 2019 finalists England from Pool D in the quarter-finals.

Eales, who steered Australia to World Cup glory in Wales in 1999, didn't discount the Wallabies' hopes of an upset victory despite their poor recent form, but predicted the winner would come from the other side of the draw.

"If you look at the teams on that side only two get through (to the semi-finals)," Eales told AAP.

"You'd have to say that of the two teams that get through from that side, they would be the favourites on current form to get through to the final.

"But to do that they've got to win a World Cup semi-final in a one-off game that could be against Australia, Argentina, England, Fiji, Wales or Japan -  and any of those teams could beat one of those other teams on the day."

Eales said the fluctuations in rankings, form and some surprise Test results mean the tournament is there for the taking.

Hosts France, the current world No.3, have appeared in three finals in the tournament's 36-year history but never won the Webb Ellis Cup, while top-ranked Ireland have never made it past the quarter-finals.

The Springboks won their third title in Japan in 2019, while New Zealand have also been crowned world champions three times.

The Wallabies have won twice, the last time back in 1999, finished runners-up twice and never missed the quarter-finals.

"It's just so open - and for the first time ever at a World Cup you would say that it doesn't matter if you finish first or second in your pool," Eales said.

"For instance, France and New Zealand are in the same pool but in the quarters they're likely to play South Africa or Ireland - who would you rather play out of those two teams?

"You know you're in for an incredibly tough game whichever one of those two teams you're facing."

Eales picked world No.5 Scotland, in Pool B alongside Ireland and South Africa as a smoky.

"People aren't talking about Scotland a lot, but Scotland can beat any of those teams," he said.

"If they were on Australia's side of the draw they'd probably be the favourites on our side with how well they've been playing."