All Blacks admiration for Japan coaches

New Zealand assistant coach Steve Hansen admits it will be strange coaching against former colleague and friend Mick Byrne when the All Blacks face Japan at Waikato Stadium on Friday.

Byrne, a former Australian rules football player with Melbourne, Hawthorn and Sydney, left the All Blacks in 2009 to take up a role as a specialist coach with the Brave Blossoms.

"It'll be like playing against your brother. You respect him but you want to beat the **** out of him at the same time," Hansen said.

"It'll be enjoyable and good for laughs. Rivalry is always a good thing."

Despite the banter, Hansen has great respect for Byrne.

"He's one of the best coaches in the world. He's a great skills coach and he knows all the mechanics and techniques," Hansen said.

"He brings lots of knowledge from the New Zealand environment and he's put that into Japan. He's very well thought of, particularly by the (All Blacks) players."

Haka plan

Byrne's role with Japan is temporary, as he will rejoin the All Blacks camp once the Brave Blossoms are eliminated from the tournament.

Japan coach John Kirwan, who was capped 63 times and scored 35 tries for the All Blacks, admitted on Monday he has a secret plan to combat New Zealand's haka.

But Hansen says it will not affect the All Blacks on Friday.

"The haka is a great thing. You saw two countries doing it on Friday night. The crowd loved it," he said.

"You hear all this rubbish about trying to scare other teams. In the end, it's all part of the culture.

"We saw another haka at the (Turangawaewae) marae. That was a pretty bloody good one.

"However I'm sure JK will come up with a good plan."