Joaquin Phoenix will be seen as Arthur Fleck alongside Zazie Beetz and Robert DeNiro.

Joaquin Phoenix says fans will be upset with the team of his upcoming film Joker for not following the character arc of the supervillain established in the original DC comics.

Phoenix, who is playing the titular character in the Todd Phillips-directed movie, said the filmmaker decided to stray from the original DC material and focus on the ''story of becoming Joker''.

"We didn't follow anything from the comic books, which people are gonna be mad about. We just wrote our own version of where a guy like Joker might come from.

"That's what was interesting to me. We're not even doing Joker, but the story of becoming Joker. It's about this man," the actor told Empire magazine.

The 44-year-old actor said when Phillips initially discussed the idea of the movie with him it sounded ''super ambitious''.

''I thought it was crazy-ambitious. Todd said to me 'I have this idea, I wanna tell the origin story of the Joker. I said 'Wow okay'," he added.

Joker also stars Zazie Beetz, Rober De Niro, Bill Camp, Frances Conroy, Brett Cullen, Glenn Fleshler, Douglas Hodge, Marc Maron, Josh Pais, and Shea Whigham. It's scheduled to release in theatres on 4 October.

(With inputs from Press Trust of India)