Although Tan originally approached him to play Fung, the reluctant gang member who still misses the simple village life he left behind, that role eventually went to Daniel Wu Yin-cho. 'I don't know if my wish affected the director, but fortunately he changed his mind,' Liu says.

Having never played a villain, Liu found it hard to bring out his dark side. His biggest obstacle was controlling his eyes, usually commended for being able to tell an affecting story.

'I'd never fired a gun and when I pulled the trigger I kept closing my eyes at the loud noise. It made me look like a coward. So I had to work hard to control my eyes,' says Liu.

'Everyone can tell I'm good-natured simply by looking into my eyes, so I may not look bad and powerful enough. But Al Pacino [in The Godfather] gave me some inspiration. I can convey a sense of uncertainty and menace by smashing things or hitting people.'

At 29, Liu still resembles an energetic adolescent. The way he relaxes between interviews by playing ping-pong and his penchant for sports allusions are reminders that he was headed for an athletic career before taking up acting at the age of 16.

Maybe it's his good looks or those soulful eyes, but directors love casting Liu in deeply sorrowful roles. Stanley Kwan Kam-pang probably has a lot to answer for.

Liu was best known for playing a down-to-earth country boy in his film debut, Postmen in the Mountains, before Kwan cast him in award-winning Lan Yu as an emotionally dependent young homosexual. His portrayal of the helpless gay man won him his first Golden Horse Award in 2001, when he was just 23.

Three years later, he clinched another best actor prize at the Golden Rooster Awards for The Foliage, playing an intellectual sent to the countryside for re-education who becomes caught up in a love triangle. Earlier roles in Dai Sijie's The Chinese Little Seamstress and Carol Lai Miu-suet's The Floating Landscape had him portraying similarly sensitive souls.

It wasn't until his foray into mainstream productions of martial period epics that Liu realised how heavily he had been typecast. The kind-hearted assassin he played in Chen Kaige's The Promise was criticised as being too effeminate while his conflicted crown prince in Zhang Yimou's The Curse of the Golden Flower was ridiculed for being gutless.

Such scathing comments may partly be rooted in audiences' dislike of the two overblown films, and Liu was so affected by it all that he still can't bring himself to watch Curse. They've also spurred him to break out of the mould.

'The two films gave me the incentive to take some tough-guy roles,' he says, pausing to choose the right words. 'But that doesn't mean I won't do mega-budget productions in the future - being able to star in such movies is recognition of your status in the industry. But I'll select my roles more carefully. I've been playing so many art films that I brought some acting habits into these two films. Next time I'll play it more simply and clearly for such commercial films - just stay handsome and cool.'

But Liu shouldn't be too downcast. After all, he was chosen to appear opposite Meryl Streep in Chen Shizheng's Dark Matter. Based on a real story, the film is about a Chinese physics student in the US who kills his lecturer when his academic aspirations are crushed by college politics. Liu plays the student and Streep a social worker he grows to care for. Their convincing performances helped the film win an award for independent productions on science and technology at this year's Sundance Film Festival.

Working with Streep was an unforgettable experience, Liu says. The award-winning actress has a penchant for improvisation, which gave him problems because at first he just spoke basic English. 'It's like fighting a smart boxer; you never know what the next move will be,' he says. 'But after a while you learn that her actions are centred on the characters. All I can do is get to know the characters well and keep up with her. Once you do that, the experience becomes very exciting and the performance is natural.'

However, his high expectations for Dark Matter were dampened by the Virginia Tech massacre in April, when a Korean student went on a shooting rampage, killing 33 people. Public release in the US is uncertain because of the sensitivity of the topic and conservative censors cancelled its scheduled screening at the Shanghai International Film Festival in June.

'I'm sad about the mainland censors' decision. The film means a lot to me,' he says. 'I worked hard on this project and working with Meryl Streep is something I can brag about for years.'

Even so, the well-received movie has opened doors to other projects overseas. Liu has been offered roles in several foreign-language films, but he's wary.

'Those roles aren't what I'm looking for,' he says. 'First, I don't know how to fight so choices are limited. Secondly, Chinese are often stereotyped in these films. Sometimes all they want is a Chinese look. And sometimes the roles are bad for the Chinese image.'

Unlike Zhang Ziyi, his former classmate at the Central Drama Academy in Beijing, Liu isn't keen on carving a career in foreign-language cinema. 'I don't have the ambition or the ability. I know how much Ziyi suffered for this and I don't want to take the same path. Chinese cinema will remain my focus.'

Despite his concerns, Liu has signed up for a French production. 'It's adapted from a novel by ... mmm ... the author of L'Amant,' he says, scrabbling for the name of Marguerite Duras.

He declines to reveal more about the project other than to say it will be shot in Cambodia and Vietnam, the setting for most Duras novels. Neither would he comment on whether his French girlfriend is involved in the production, saying only that 'I have a French mentor now'.

But Liu is happy to be working in a genre he's familiar with. 'It's good to do an arty film again after doing so many fights,' he says.