Movie details rise of a world champion.

Notoriously private former All Blacks captain Richie McCaw let a camera follow him for 18 months to make the movie expected to set the New Zealand box office alight.

Detailing McCaw's entire life, from his beginnings in the small town of Kurow to a rugby superstar who led the All Blacks to consecutive World Cup wins, Chasing Great is set to be a huge hit.

As fans count down to the September 1 cinema release, McCaw's agent, Dean Hegan, said while the rugby great was used to the media spotlight during his 148-test career, it had taken some time to get comfortable in the role of movie star.

"It took him a while to get his head around being the focus of a movie. He's a humble sort of a bloke," Hegan said.


He said the McCaw camp hopes Chasing Great will be a smash-hit beyond the traditional rugby markets of New Zealand, Australia, South Africa and England, as it's a compelling human interest story as much as a tribute to a sporting great.

"We hope it'll be well received by all markets.

"Richie felt he could inspire kids to realise that people from ordinary backgrounds can achieve great things if they put their mind to it."

Since the movie was announced McCaw, who will go to the Rio Olympics next month to support fiancee Gemma Flynn in the Black Sticks' bid for hockey gold, has acknowledged how strictly he controlled the window into his personal life for so long.

But now, he's ready to open the curtain a little.

"I was always quite keen to make sure I kept some of the private stuff private, not for any reason other than I just felt that was the right thing to do," he said earlier this week.

"But I got to the end and one of the reasons for doing this is, I took a lot out of the opportunities I got and this is a chance to try and inspire perhaps some young kids or show that you don't have to be given some superhuman talent or anything to fulfil your dreams. It's not something magic, it's a bit of dedication, hard work - those sort of things that allow you to fulfil those dreams."

The film is directed by Justin Pemberton and Michelle Walshe - who McCaw previously worked with on promotional campaigns involving the All Blacks.

"This is a film for New Zealanders young and old," Walshe said. "It will really connect with anyone interested in what it takes for an ordinary person to achieve phenomenal accomplishments."

Pemberton said McCaw made for an exciting character study.

"Ultimately what grabs me are stories about people who are extraordinarily driven, and the sporting arena is rich with inspiring passionate people," he said.