"I do seem to remember her spitting up coffee the first time I sang, so that felt good, that was exciting, and made me feel confident," he recalled.
He collaborated with the renowned 'Shallow' singer to establish a musical rhythm that would underscore the development of their characters in the eagerly awaited film.
"Gaga was always very encouraging of just, 'Go with what you feel, it's fine'," Phoenix said. "For somebody who's not a performer in that way, it can be... uncomfortable to do that, but also very exciting."
He also shared the importance of music for his character.
"It was important to protect that with poor phrasing and occasional bum notes," Phoenix added. "Arthur grew up hearing his mother play these songs on the radio. He's not a singer, and he shouldn't sound like a professional singer. He should sound like somebody that's taking a shower and just bursts out into song."
The first 'Joker' was a huge success, both critically and commercially. It was nominated for 11 Oscars, with Joaquin Phoenix winning Best Actor and Hildur Gudnadottir winning for Original Score. It became the highest-grossing R-rated movie ever. Phoenix reprises his role as Joker in the sequel, and Lady Gaga joins as Harley Quinn. The movie will mostly take place in Arkham Asylum.
The supporting cast includes Brendan Gleeson, Catherine Keener, Jacob Lofland, and Harry Lawtey. Zazie Beetz returns as Sophie from the first film. The sequel is said to be a musical, building on Phoenix's dancing scenes from the original. Todd Phillips returns as the director of 'Joker: Folie a Deux.'
The sequel to the 2019 film 'Joker' will be released in theatres on October 4, 2024, after premiering at the Venice Film Festival. The first 'Joker' movie won the Golden Lion at Venice in 2019, according to The Hollywood Reporter.