"Is this real?"

The Euphoria actress is set to portray boxer Christy Martin, dubbed the 'female Rocky', in the yet-to-be-titled movie.

Sweeney revealed her background in combat sports helped her in the role.

Speaking to Deadline, she said: “I grappled and did kickboxing from 12-19 years old. I’ve been itching to get back into the ring, train, and transform my body.

“Christy’s story isn’t a light one, it’s physically and emotionally demanding, there’s a lot of weight to carry. But I love challenging myself.”

Christy Martin rose to fame in the 1990s and became one of the first female boxers to be inducted into the International Boxing Hall of Fame.  

Sweeney continued to talk about what an inspiration Martin had been, she said: “Christy Martin not only legitimised female boxing, she overcame gender stereotypes, and fought through emotional, physical and financial abuse.

“I’m passionate about the fighting world, Christy’s story shines a light on her incredible rise to the top while showing the struggles of fame behind the curtains.

“I feel compelled to tell a story about a woman who faced so much adversity and didn’t allow it to defeat her. It’s powerful, and emotional.”

Martin, who produced a 49-7-3 record, not only overcame adversity in her career but in her personal life as well.

In 2010, she was stabbed several times and shot by her husband James Martin who then left her for dead.

Miraculously, she survived the attack and he was arrested and found guilty of attempted second-degree murder.

In new pictures shared by Sweeney to her Instagram account, fans have been left impressed by the 27-year-old's transformation for the role.

"Didn’t know Sydney was jacked like that," one person commented.

A second put: "I thought she was Billie Eilish."

"This transformation truly threw me off," a third put. "I’m excited to see what you do with it."

A fourth joked: "Chat is this real?"

The biopic is yet to get a name, but is set to also star Tony Cavalero, Merritt Weaver and Ethan Embry.