Maverick film director Robert Rodriguez credits his eight-year old son RACER for creating his new movie SHARKBOY AND LAVAGIRL IN 3-D.

The Sin City maker's son dreamed up the adventure story - which was originally intended to be a children's book - but Dimension Films loved the idea so much they decided to make it their first big 3-D release.

The 37-year-old admits, "He's my Frank Miller on this one, I guess. He comes up with the ideas that only an eight-year-old boy could come up with.

"At first, I was just going to draw it as a storybook.

"Then the studio rang and said they wanted to do another movie in 3-D. And I didn't have any ideas so I just said, 'Er, Sharkboy and Lavagirl... In 3-D?'. And they said it sounded great.

"I told the studio it was my son's idea and they're like, 'We're signing him up."