'Joker' director Todd Phillips has revealed that Joaquin Phoenix, whose unnerving performance the film is generating early Oscar buzz, would sometimes walkout from the set in the middle of a scene.

In a cover story on the 44-year-old actor in The New York Times, Phillips revealed that they had several fruitful creative differences over the character, one of the most iconic and complex villains in the Batman lore.

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Phillips said Joaquin Phoenix "lost his composure on the set, sometimes to the bafflement of his co-stars".

"In the middle of the scene, he'll just walk away and walk out. And the poor other actor thinks it's them and it was never them  it was always him, and he just wasn't feeling it," he told The New York Times.

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Joaquin Phoenix, however, would always return after taking a break. 

"We'll take a walk and we'll come back and we'll do it," is what Joaquin Phoenix told Phillips after a particularly tense moment.

Robert De Niro, who stars as a late-night show host in the movie, was the one person that Joaquin Phoenix never walked out on. De Niro said Joaquin Phoenix was a 'consummate professional'.

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"Joaquin was very intense in what he was doing, as it should be, as he should be," De Niro said. 

Phillips is not worried about how Joaquin Phoenix will handle the publicity of the film, saying, "If he goes on Jimmy Kimmel and walks off after two minutes, I'd be like, That's my boy'. He follows his own rhythm." 

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Watch Joker trailer here: