Mos definitely

For an international hip hop star, now appearing in a Pulitzer prize-winning play, Mos Def sure is one unassuming guy. 'You really should talk to George [Wolfe, the director] or Jeffrey [Wright, his co-star] or Suzan-Lori [Parks, the writer]. I'm a bit shy about the media. Is this gonna be a big thing?' He keeps his gaze fixed somewhere else, and squirms.

I'm not that bad to talk to, am I? 'No, no, no, it's not you, it's me... uh oh, that sounds like a line... how many times do people say that? It's not you, it's me. It's not even us, it's just me.' He grins, massively, and the room lights up.

If it's quite a shock to find a rap star who's so shy, you may think it's still more surprising to be interviewing him about his debut on the London stage. But Mos Def's professional theatrical career predates his musical success and, despite an increasing number of movie roles, he has always wanted to return to the boards. Suzan-Lori Parks's Topdog/Underdog inspired him to make the leap and soon he was on Broadway.

'Topdog was the first time I had done a play in ten years. I saw it several times at the Public Theater [when Don Cheadle played the role], then I got the call from George out of the blue.

'It was like going to see the Duke Ellington Orchestra and looking at Billy Strayhorn and thinking, "Wow, man that's so cool," and then the Duke calls you: "Listen, Billy's not going to be able to make this next tour, you want to audition?".'

Taking on the role of Booth proves Mos Def doesn't like to do things by half: Topdog/Underdog is an intense, demanding two-hander, about two brothers locked in a devastating love/hate relationship.

'This role was a huge vote of confidence in me because there's no place to hide in a two-person play,' he acknowledges. 'I was thrust into this situation, but I stepped into it as well. I was invited and then I accepted, and then after I accepted I was like, 'What the f**k am I doing? Who do I think I am?'

Of course, Mos Def being how he is, quickly points out that he couldn't have done it without the people around him. He cites Jeffrey Wright (star of Basquiat) as one of his favourite actors, and as for Wolfe, he says: 'I won't work with a better director. If I could work on projects that only he directed I would do that. He saw something in me that I didn't even see, and I'm grateful for that.'

Booth is, in many ways, a deeply unpleasant character; a man driven by past and present hardships to retreat into fantasies and dreams of making his fortune by mastering a con trick.

His brother, Lincoln (Wright) is also trying to break free, in his case by subverting his identity: 'whiting up' to play Abraham Lincoln in a macabre fairground show where people pay to pretend to assassinate him. 'They have a nasty side: as anybody with their history would,' says Mos Def. 'They can be pretty cruel, but the world has been pretty cruel to them. It's just a means of them surviving.'