Wicked director explains why the movie's version of Defying Gravity is different to the show's: "We had to break that up a little bit, which is scary"

'Defying Gravity' is one of the most iconic musical theater songs of all time, which makes translating it from stage to screen a particularly tall task. That's the challenge Wicked director Jon M. Chu was faced with in his new adaptation – made even more intimidating by the fact that 'Defying Gravity' closes the entire film, since the movie covers Act 1 of the musical (with Part 2 finishing the story when it arrives next year).

"The alternative was not possible, to be honest," Chu tells us of dividing the story when we meet with him in London. "We tried to make it into one movie, and you had to rip out songs and it became not Wicked. They had tried for 20 years to do that. I think the decision to make it one really opened the doors to like, 'Okay, we have to believe these characters.' You get away with things on stage that you can't get away with in a movie. The audience is more skeptical in a movie, and so the emotional turns for the actors and for the characters have to be very solid. So it came out of a necessity more than anything."

And, as Chu explains, this led to some changes for the musical's most famous song. "But something like 'Defying Gravity,' the song, if you just use the song itself the way it's used in the show, it doesn't actually feel like the end of this epic journey that we've gone on," he says. "So we had to break that up a little bit, which is scary. And we questioned ourselves at every turn. We did not make decisions lightly. We actually could make decisions and go backwards. We tried all versions, always. But in the end of the day, it was like, 'I'm rooting for Elphaba to have this for herself, and she can't just get it. She has to earn it, too.' She knows at this moment that you don't have to prove yourself to anyone. She has to prove it to herself. How do we show that through this number that already exists? And you're not going to add new words to it. So what are you going to do?"

Chu adds that one of the changes made to the way the song plays out "brings back all the stuff in the movie that we've seen, all the doubts that have been put upon her, that she has to make a decision that is for herself – or for this little girl, for whatever way you want to interpret it – so that when she says, 'It's me,' the ultimate goal for us this whole movie, we've been saying, 'It's not for anybody else, it's for me,' that she stands up and sings 'Defying Gravity.'

"And I think that was something that, had we not cut it into two movies, you couldn't have those moments," he continues. "And so I think the audience will stick with us on that when you see the movie."

Wicked is in theaters this November 22. For even more on the movie, check out our Wicked review for our spoiler free verdict, or see the Wicked first reactions. You can also fill out your watchlist with our guide on all the upcoming movies of the year.