But Duco promoter Dean Lonergan said the actor was a "fit bugger" who trained five times a week.
The 52-year-old's bout will be filmed for an episode of his reality show, The Life and Times of Temuera Morrison.
"We've nearly finished making the show, we're at the end of it. We've got one more episode to shoot," he said.
"Cameras have been following me around the world looking at what it's like to be a New Zealand actor. I'm just talking with producers about how we film the boxing. It'll be good."
Morrison's television series is expected to go to air in October. It is being produced by Black Inc Media, the makers of the Australian-Maori reality series The GC. It is reported to have received nearly $425,000 in public funding from Rautaki Maori.
Morrison said reality TV was cheaper and easier to produce, and quick to get to air.
"I want to reinvent myself and reality television is the way to go for me," he said.
Morrison is best known for his role of Jake the Muss from the 1994 move Once were Warriors.
He has also starred in blockbusters such as the Star Wars series, Green Lantern and more recently NZ film Mt Zion.