George Gregan confident that Australia won't be tipped over by Wales at World Cup

Wallabies great George Gregan says every northern hemisphere power will pose a threat at the Rugby World Cup, although he questions whether Wales have the attacking strike power to go all the way.

The former Australian captain says Europe's best have clearly advanced since the 2015 tournament, with none reaching the semi-finals, and it's conceivable Japan might offer up the first northern winner since England in 2003.

Gregan is most taken by the English, who he's tipping to mount a compelling campaign under his former Brumbies and Wallabies coach Eddie Jones.

Wales have also impressed him during their ascent to world No.1 status, but Gregan believes Warren Gatland's team might lack the sparkle required on the likely hard and fast surfaces.

"They're pretty comfortable with how they play, Wales," he said.

"I just have my doubts whether the way they play is going to be conducive to scoring a lot of points in a World Cup, and the conditions in Japan will be very conducive to keeping the ball in hand and playing."

Australia meet Wales in their second pool match, on September 29, in Tokyo.

A 13-Test winning streak against the Welsh ended last November with a tense 9-6 loss in Cardiff, where the hosts produced the sort of pressure rugby that had been their hallmark of the past 18 months.

Gregan said Ireland had proved they would be powerful but saved his most lavish praise for England, impressed by their scoring of eight tries a year ago in the narrow three-Test series loss in hard South African conditions.

"They have the ability to score points, a lot of points, and then they can defend well," Gregan said.

"Eddie being Eddie, they'll be organised and gearing towards playing their best football at the end of the tournament."

Gregan, the only Australian to compete at four World Cups, said current form wasn't a good indicator as teams were at different stages of experimentation.

He believed Australia could challenge for a third crown, regardless of inconsistent results this year.

They routed the All Blacks in Perth but were whitewashed by the same opponents a week later in Auckland.

"In the Rugby Championship, you mightn't start well but you can bounce back in a week or two and correct stuff," Gregan said.

"But if you don't get it right on the day from the quarter-finals onwards at the World Cup, you're out.

"What the Wallabies showed in the last two weeks is that on any given day, they can beat the best team in the world and really outplay them that night."

- AAP