AceShowbiz - Joaquin Phoenix has apparently begun his transformation to play Batman's villain Joker. The Golden Globe Award winner and the three-time Academy Award-nominated actor was looking noticeably thinner in New York City on Wednesday, August 29.

The "Her" star was spotted while walking around the town in a navy blue pullover shirt and dark jeans. He wore black sunglasses and a pair of sneakers, and carried a backpack, while smoking a cigarette on the streets.

Joaquin Phoenix is about to begin production on his Joker origin movie and he's noticeably thinner - see the new pics https://t.co/cIOM4jqpUw

— JustJared.com (@JustJared) August 30, 2018

Phoenix was cast in the lead role for "Joker" in July following months of rumors. The project is said to be separated from the DC Extended Universe, thus it will not interfere with Jared Leto's portrayal of the Clown Prince of Crime in a potential "Suicide Squad" sequel and planned spin-offs.

"I take a lot of time and consideration when making decisions and what I'm gonna work on," he told Collider after picking up the role. "It feels unique, it is its own world in some ways, and maybe, mostly, it scares the f**k s**t out of me, or something." He added that the upcoming movie "might as well be the thing that scares you the most."

The upcoming Joker movie will tell an origin story of the signature villain of Batman, which is described as a gritty character study but also a broader cautionary tale of a man disregarded by society who becomes the ultimate supervillain.

Principal photography is expected to begin in September for an October 4, 2019 release in the United States. Todd Phillips is slated to serve behind the lens, in addition to writing the script along with Scott Silver.

Robert De Niro, Frances Conroy, Zazie Beetz and Marc Maron will also star in the movie, while Alec Baldwin recently confirmed he dropped out of the project, for which he was cast as Bruce Wayne's father, due to "scheduling" issues.