Richie McCaw says his move to number eight for Saturday's Test against Ireland isn't as big a deal as some are making it out to be.

The All Blacks captain moves to number eight for the Hamilton clash following Kieran Read's concussion, with Sam Cane starting in McCaw's usual position of openside flanker and Liam Messam coming in on the blindside.

It will be the 100th time McCaw has started a Test match but though it's his first start at number eight, he's not concerned given that he played the second half there in last week's 22-19 victory over Ireland in Christchurch.

"At the end of the day, apart from a little bit of stuff at set piece time, you don't change your game a whole lot," he said.

"I'm making sure I'm up to speed with roles at the foot of the scrum and at the lineouts, but making sure we work together as a loose forward trio is a key tomorrow."

McCaw said he's confident the openside role is in good hands with Sam Cane, who starts for the first time on Saturday after playing the second half last week.

"He couldn't have got a more pressure situation to come in and have his first Test. He did particularly well I thought, like he'd been around for a while."

As well as starting for the 100th time for the All Blacks, McCaw is in line to become the most successful Test rugby player of all time if the All Blacks win as it would take him to 94 wins, one ahead of former Australian halfback George Gregan.

But he says the numbers don't matter much as the task of the game at hand is most important, especially given how close Ireland pushed the All Blacks last week.