Maths whiz: All Blacks to win Rugby World Cup

Stefan Yelas correctly predicted the outcome of the 2011 World Cup. Photo / Brett Phibbs

Spoiler alert: The All Blacks will win a trans-Tasman showdown in the Rugby World Cup - but only just!

Melbourne-based Kiwi maths brain Stefan Yelas - who correctly predicted the outcome of the 2003 and 2011 World Cups - is backing the men in black to secure a four-point win over the Wallabies in the final at Twickenham on November 1.

Yelas' prediction - which obviously requires the All Blacks to beat the Springboks early tomorrow in the first semifinal - is based on a maths formula he devised for a masters degree 12 years ago.

Originally he backed the All Blacks to enjoy a four-point win over England in the final, but was forced to redo his predictions after the host's stunning failure to escape pool-play.

Based on his stats, Yelas says the All Blacks have a 38 per cent chance of winning the World Cup, while the Wallabies - who smashed England 33-13 in their group and play Argentina in the second semifinal on Monday - have a 26 per cent chance of victory.

"The All Blacks are still favourites and most likely to win - but only just," Yelas told the Herald on Sunday from Melbourne.

"We've crunched all the data again and it's come out with Australia not only being the next team in line, but they've reduced a 16 per cent gap from when England were second favourites, to 12 per cent with the Aussies right behind the All Blacks. What a final that would be."

Yelas said he was surprised the English crashed out so early, with home advantage a key element which is factored into the probabilities and historically, has been a defining element in successful forecasts.

Yelas has the trans-Tasman nations way out in front as the most likely winners, with South Africa third favourites carrying just an 17 per cent chance of winning.

Each team's chance of winning:

All Blacks 38%
Australia 26%
South Africa 17%
Argentina 5%