'Wicked' director Jon M. Chu demanded Ariana Grande prove she could "overcome" her pop star image before she was cast as Glinda.

The 31-year-old singer stars opposite Cynthia Erivo as the 'Good Witch' in the musical blockbuster, though Chu, 45, insisted he would only consider Grande for the role if she could demonstrate she could put her pop star persona aside for the part.

The filmmaker told Deadline: "[She] had to overcome the Ariana Grande image in order to do it. And I know how hard it is.

"I've seen actors who do their first lead in a movie, and that's not easy. That also takes skills and that takes actual craftsmanship. That experience can happen."

While her audition process was a challenge, the 'Crazy Rich Asians' director said Grande ultimately won the role of Glinda after demonstrating she "understood the nuance of the character".

He said: "Every time she came in, Ari was the most interesting person. She was funny, she was emotional. But more than that she understood the nuance of this character in a way that felt so real it wasn't a performative version of it.

"And by the end it was like, if the audience feels like this is a discovery, they're going to see things they've never seen in Ariana Grande before."

'Wicked' - which also stars Jeff Goldblum, Michelle Yeoh, Peter Dinklage, Jonathan Bailey and Ethan Slater - follows Elphaba (Erivo) and Glinda (Grande) as they try to find their place at Shiz University, only for their friendship to be put in jeopardy once the Wizard of Oz forces the pair's paths to diverge.

While Chu was initially apprehensive about casting Grande in 'Wicked' due to her successful music career, the 'In The Heights director knew he wanted 37-year-old Broadway star Erivo to play Elphaba, though was unsure whether Universal Pictures would want a fairly unknown actress to lead the film.

He said: "We'd be like, 'This is a coup!' They don't even know. They know what we're doing inside this movie right now. And it felt we were co-conspirators, with Ari of course."

Reflecting on Erivo's casting, Chu said it was "probably the smartest thing [he] ever did in [his] life".

He explained: "She looked at this as a very personal story and she brought those things of what it feels to be othered, what it feels like to have people constantly tell you, you need to act this way or that way for people to accept you, that you have to prove yourself to someone.

"But she's also the same person who at drama school dreamed, dreamed big, that she would be able to get there. And those dreams were also crushed, whether it's at drama school or elsewhere."

'Wicked' is set to receive its sequel 'Wicked: For Good' in November 2025.