Racer X, revealed

When imagining a chance encounter between actor Matthew Fox and, say, a father and his grade school son, one would probably peg the dad as the one having the glint of recognition, making the awkward approach and perhaps pleading for some hint about what's coming up on "Lost," the twisty, freaky, grown-up TV drama that has starred Fox for the last four years.

A few weeks ago, though, Fox saw how the future of that fan equation might look after he caught an advance screening of his new movie, "Speed Racer," the Wachowski brothers' long-awaited film adaptation of the iconic Japanese cartoon series from the late '60s.

"I've never done anything that kids can see," Fox says. "And in the bathroom afterwards, this little boy was talking to his dad like, 'It's so awesome! We have to see it on Imax, Dad!' And he was tying his shoelace, and I said, 'Hey, how old are you?' " Here, Fox reenacts the boy's slow head lift, mimics his nonchalant response: " 'I'm 8,' " and then the widening eyes as he looked up and whispered in awe, " 'You look like Racer X!' "

The 41-year-old actor laughs at the memory of it, with the glee of someone as excited as that boy who got to meet the candy-colored family flick's mysterious, masked avenger/protector. "That was a really cool moment for me and a big part of why I wanted to be a part of it, you know?" says Fox. Watching his own kids -- Byron, 6, and daughter Kyle, 11 -- experience the movie they've been anxiously awaiting since Fox was cast over a year ago will be "an absolute highlight of my time in this business," he says.

What Fox's kids later saw on screen at the movie's premiere was their father maneuver a physics-defying fantasy car and waylay bad guys, all in the name of saving Speed Racer (Emile Hirsch) from evil on the road and corruption in the sponsorship world. What Fox had to do on Berlin sound stages last year to achieve this, though, was to hone the art of green-screen acting and train intensely for martial arts sequences while wearing a skin-tight leather racing suit and eye-shielding skull wrap.

"When you take on something like this, which I was incredibly excited to do, there are nights lying awake in bed where you start to think there are so many ways it can go wrong," he says. When asked to elaborate, Fox says, "Just not pulling it off. Your job as an actor is to convince, to find some sort of truth in it. You have to believe, and then your belief in it will be contagious."