Andy Ruiz has arrived in New Zealand for next Saturday's showdown with Joseph Parker for the vacant WBO heavyweight world title. Photos by Peter Meecham.

Parker admits his boxing career has been physically draining, yet he has never felt mentally sharper.

The unbeaten Kiwi heavyweight says he goes into next week's title fight feeling more focused than before any of his previous 21 fights.

Recruiting a mental skills coach, former New Zealand soccer international Ceri Evans, has honed that element of his preparation for the fight in Auckland on December 10.

Parker has found it easier to cope with missing a number of important family milestones in Auckland while he was sweating it out in a training camp in Las Vegas.

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His first child, Elizabeth, was born two weeks ago while Parker also missed his sister's wedding and his mother's 50th birthday.

"There's a lot of reasons why I should be motivated to go out there and give it my best," the 24-year-old said.

"This is my time. I've never felt mentally sharper."

Parker says he visited Elizabeth for the first time when he arrived home over the weekend.

Lessons on changing nappies will have to wait, however.

"I need to protect these hands," he smiled.

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In his first press conference ahead of the fight, Parker found himself hitting back at the comments of his own trainer.

Kevin Barry told journalists he rated the more experienced Ruiz as favourite, believing the unbeaten Mexican had even faster hand speed than the nimble Parker.

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"I respect Kevin and his opinion. Andy does have fast hands but I believe I'm faster," Parker said.

"Kevin did say that Andy was the favourite but he didn't say that I was going to lose."

Parker appreciated the relatively short, intense nature of the Las Vegas camp at the end of another hectic year.

It will be the Kiwi's 14th fight in the space of 2-1/2 years.

"The body has taken a beating in training and in fights but I'm ready for this," he said.

"I get two months off afterwards so I'm going to give it everything that I have. Whatever's left in the tank."