As a film-maker you do not get given gifts like the story of the tightrope walker Philippe Petit, who walked between the twin towers, very often - it is like a real-life fairytale. A man has an impossible dream, and that dream is to create something beautiful, but there are so many obstacles in the way of that objective, and all of them seem insurmountable. It's like a classical myth in the scale of its audacity.

As I sit here in LA, panicking about how I am going to find a suit, thinking about the flurry of awards that we have been mercifully and thankfully nominated for, I've been wondering what it is about Man on Wire, a documentary, after all, that seems to have struck a chord. I think it pertinent that the film appeared around the time that Batman was released. Batman was typical Hollywood - huge budget, huge special effects and lots of technical gimmickery. What we have in Man on Wire is the opposite. It's a documentary that shows you the very limit of human possibility. What Petit did was real, and in the film you get to know him, and, though he won't like me saying it, to comprehend that a man's life is ultimately at stake. Petit is a real-life superhero.

It is also a film about the New York that I first encountered in the Seventies. It exists in a pre-9/11 world. There is now a climate of fear in the world, and particularly in New York, that the film predates and explores indirectly. What Petit did was to devise a brilliant spectacle to create, not destroy, something. He used the towers as a kind of backdrop, a stage. What he did was incredibly beautiful and surprisingly innocent.

Petit will, of course, be with me at the ceremony. He is thrilled that his walk has had this sort of second life. We both find the whole thing slightly ridiculous, but in a good way; the joke is not on us. Sadly, if we do win, Petit can't come up to the stage - the rules about accepting your award are very strict. I'd love to think we could plot something - he is, of course, the master plotter - but I think the Oscars are finally his match.

Before Man on Wire came along I really was struggling. It was a difficult period. I would make a film and it would never lead on to my making another one; each time it was starting from scratch. But this film has allowed me to have a bit more freedom and choice. Last Sunday I put the finishing touches to an adaptation of David Peace's Red Riding, 1980 for Channel 4, so the next year, at least, looks good. Then it will probably be all over again, of course.

Given that I may not get the chance tomorrow, I would like to finish this by saying thank you to my brother Tony - he is someone who, when I have not been able to work, has supported me in my wretched career. He works for the police. “His ne'er-do-well brother finally makes good”, I think, is the headline for him.

James Marsh is the director of Man on Wire, the winner of Bafta and Sundance accolades and nominated for Best Documentary in the Oscars tomorrow night

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