U.S. actor Brad Pitt, who stars as Oakland Athletics' general manager Billy Beane, arrives for the world premiere of the film "Moneyball" in Oakland, California September 19, 2011.[Photo/Agencies]

Brad Pitt is "amazed" to star in baseball film 'Moneyball' because he knows so little about the sport.

The 47-year-old actor plays former Major League player and Oakland Athletics manager Billy Bean in the film but admitted in real life he chose wrestling and diving over baseball at high school.

He told Sports Illustrated magazine: "It's shameful how little I know about baseball. I'm amazed they let me do this movie.

"Baseball and I didn't get along that well. I wrestled one year in high school. I dived one year. Everything but baseball."

However, he was attracted to the role because it is based around his home state and gave him a chance to tell a good underdog story.

He added: "I'm an Oklahoma-Missouri boy, so I'm no stranger to a bit of dip. So really, I was just revisiting my roots. I'm a sucker for the underdog story."

Brad feels the film is unconventional by today's Hollywood standards, and instead compares it to 70s movies 'The French Connection', 'One Flew Over the Cuckoo's Nest' and 'All the President's Men'.

He said: "What we were trying to do is tell an unconventional story in the Trojan horse of a conventional baseball movie.

"In scripts today, someone has a big epiphany, learns a lesson, then comes out the other side different.

"In these older films I'm talking about, the beast at the end of the movie was the same beast in the beginning of the movie.

"What changed was the world around them, by just a couple of degrees."