Ireland's earth-moving victory over Australia has turned the Rugby World Cup on its head.

The stunning 15-6 victory at Eden Park, ranked by some as Ireland's greatest ever rugby triumph, has - for now - scuppered hopes of a blockbuster final between the All Blacks and Wallabies.

Instead, unless there is another upset in one of only a handful of pivotal pool games remaining, the October 23 final will feature a southern hemisphere team versus a northern hemisphere nation for the sixth time.

Australia and South Africa are suddenly on a quarter-final collision course, with the winners to square off with New Zealand in the semis - unless the All Blacks lose their likely quarter-final against Argentina or Scotland.

In the other half of the draw, England are on track to meet France in the first phase of knockout play, with the victors probably left to face resurgent Ireland or Wales in the semis.

"Let the Tri-Nations sort out one half and the Six Nations sort out the other half," Ireland coach Declan Kidney said after masterminding Saturday night's tournament-changing 15-6 win over Australia.

"It's only a World Cup if a northern hemisphere side plays a southern hemisphere team in the final."

The only final involving two Tri Nations superpowers came when the Springboks beat the All Blacks in extra time in 1995.

It seems the only plausible way for an all-southern hemisphere final showdown can eventuate now is if France, not for the first time, surprise New Zealand at their Eden Park fortress on Saturday.

Such a result would relegate the All Blacks to runners-up status in Pool B and thrust the perennial tournament favourites into a quarter-final against England - on the opposite side of the draw to where the Wallabies and Springboks are heading.

Less likely is Australia still topping Pool C with wins over the USA and Russia and Ireland falling to Italy in the last group encounter in Dunedin in two weeks.

Wallabies coach Robbie Deans, for one though, is not expecting Ireland to give up their advantage.

"I would suggest if they can maintain that sort of level, they're among a number of sides that can win this World Cup," Deans said.

It was Ireland's first victory over Australia in five World Cup encounters after the heartbreak of two one-point defeats - 19-18 in the 1991 quarter-finals before the Wallabies raised the Webb Ellis Trophy for the first time and 17-16 in the pool phase in 2003.

"We're fairly pleased with it," Kidney grinned in a massive understatement.

"I suppose when you've played a team five times in a competition, it's nice to get one over them eventually.

"But it will be meaningless if we don't win the other two matches because we're a long way from qualifying out of our group yet."

In Sunday's games, England climbed to top spot in Pool B with a 41-10 bonus-point win over Georgia in Dunedin after Wales edged out Samoa 17-10 in a bruising Pool D contest in Hamilton.

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