He has an ulterior motive, but All Blacks coach Graham Henry is backing the Wallabies to knock over rugby world champions South Africa in Perth and Brisbane.

The New Zealanders need their trans-Tasman cousins to do them a huge favour if they're to have a realistic chance of sneaking away with a fifth straight Tri Nations title.

A win by the undefeated Springboks next Saturday at Subiaco Oval or at Suncorp Stadium the week after would virtually assure them of a third southern hemisphere trophy.

The unbeaten Springboks currently sit on 12 points from three matches, New Zealand are on eight from four games and winless Australia are languishing at the bottom with just two bonus points after three.

"We need the Aussies to get up in the next two Tests, don't we?" Henry told a press conference after his side secured the Bledisloe Cup for another year with a 19-18 victory over the Wallabies at ANZ Stadium on Saturday night.

"And I think they're good enough to do the job, they just need to have that rub of the green I suppose and hopefully they can do that and that gives us a sniff."

A less pungent scent lingers in the nostrils of Wallabies coach Robbie Deans, who was talking up a mathematical miracle for his side on Sunday.

"We haven't given up on (the Tri Nations title), no, it's not out of the way," Deans said.

"It can be done."

And Deans went as far as suggesting he'd be happy to help out his former rival for the All Blacks job Henry when the Wallabies meet silverware-hungry South Africa.

"The one thing you'd say about (South Africa) this year is they'll be very excited about adding the Tri Nations to what they've already got (the World Cup) and they'll see Perth as the place to do that," Deans said.

"That's very close to home for them, they get a lot of support there, so hopefully we'll get a lot and we'd love to help Graham Henry.

"They'll be targeting it because it's the next outing and they can wrap it up.

"They're in a position to control their own destiny."

Meanwhile, Henry added to the growing body of evidence that the Australians lack the mental steel to win the big Tests by crediting his side's victory to that very factor.

Asked what the difference between the sides was after winning five of six Tests against Deans-coached Australian teams, Henry said: "There's not that much in it really.

"At the end of the day our guys just showed a huge amount of intestinal fortitude, that mental toughness was the winning.

" ... It just shows the guys have got the guts to hang in and keep going and that's a rare character, something every special in the group."

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