Rain, 25, made his Hollywood film debut in Andy and Larry Wachowski's new film, Speed Racer, which also stars Emile Hirsch, Christina Ricci and Matthew Fox.

Rain had ditched his usual golden boy appearance when he appeared at The Peninsula this week in favour of geek-chic - shoulder length hair and a pair of black-rimmed spectacles - to promote the Hong Kong release of Speed Racer.

He said he had grown his hair for his lead role in Ninja Assassin, his second Hollywood film. The film is also directed by the Wachowski brothers, and shooting will begin later this year. Rain said he had landed the part thanks to his performance in Speed Racer.

Some people questioned his decision to take a minor role and play the slippery character Taejo, who betrays his friend, saying it could harm the positive image Rain has cultivated for the past six years, but the star disagreed.

'For an actor jumping from the Asian screen to Hollywood, it's not normal to play a lead right away. I don't think I have seen any actor who has ever done it before,' he said. 'Filmmakers don't know you and what to expect from you. You need to be able to secure a good spot in order to move up from there, step by step. I think playing a minor role is normal and it feels right.

'The first film helped me to build up my networks - what's better than having two famous directors as your close friends? I have now proved myself to them and they cast me in the lead in my second Hollywood film,' he said.

The original Speed Racer cartoon series evolved from Japanese manga Pilot Ace by comic artist Tatsuo Yoshida. The comic was a hit in Japan and was turned into an animated television series called Mach Go Go Go in 1967. Six months later, the cartoon was dubbed into English as Speed Racer and released in the US. The sibling directors have been addicted to it since childhood.

To stay true to the original story, the film is filled with computer-generated imagery, and visually it's impeccable. But that made it a challenge for the actors, as they had imagine their surroundings.

'We were put in costumes pretending we were competing in an extreme car race,' said Rain. 'The shots might look very simple but they weren't at all. Apart from the green screen, nothing else was there, and it was very difficult to relate your emotions to the empty setting. It took me a couple of days to get used to that sort of filming. But I think the directors are so talented in what they do that if they can imagine something, they can make it happen on screen.'

It looks as if acting projects will be Rain's priority in the next couple of years until he cements his conquest of Hollywood, but he is not ready to put aside the musical talent that shot him to stardom six years ago.

'I like both acting and singing,' he said. 'I'll never choose one over the other.'

Speed Racer opens on May 8