Sydney Sweeney shows off muscles while revealing transformation for trailblazing female boxer role

Sydney Sweeney has offered fans a glimpse of her new look as she gets set to play Christy Martin , America’s most successful female boxer of the 1990s.

The as-yet-untitled sports biopic is being helmed by Animal Kingdom director David Michod.

In a post on Instagram , Sweeney wrote: “well the cats out of the bag thanks to some paps in bushes so here’s a little bts from my film im working on right now.

“over the past few months, i’ve been immersed in training to bring to life the story of an incredible woman—a true champion who fought battles both inside and outside the ring.

“her journey is a testament to resilience, strength, and hope, and I’m honored to step into her shoes to share her powerful story with you all. more to come soon :)”

The film, which Michod co-wrote with Mirrah Foulkes, started production at the end of last month.

It is also set to star Ben Foster, Merritt Wever, Katy O’Brian, Ethan Embry and Jess Gabor.

An official description of the film reads: “The film tells the unbelievable true story of formidable Christy Martin, who rose to fame as America’s most successful female boxer in the 1990s.

“A naturally gifted fighter, Christy’s life transformed in 1989 when she met her manager, and later husband, Jim Martin. Breaking boundaries, she became the first woman to sign with iconic promoter Don King, and the only female boxer to appear on the cover of Sports Illustrated.

“Christy’s charisma, good looks and unwavering resilience in the ring won her a wide fan base and propelled her to become welterweight champion. Behind this well-honed public persona, Christy tackled personal demons, toxic relationships and an attempt on her life, proving that a fighter’s hardest won victories aren’t always in the ring.”

In 1996, The Independent ’s Tim Cornwell covered Martin’s fight against Bethany Payne in Las Vegas.

“Christy comes out of the corner weaving like an adder, with her head held low in the style of her hero, Mike Tyson,” wrote Cornwell. “She punches to the head and body, then unlooses a right followed by a left. Payne shivers like a tree, staggers and reels in a kind of slow-motion dance as the crowd roars and the referee stops the fight.”

Martin won that fight on a technical knockout, part of a seven-year unbeaten streak.

The biopic, which does not yet have a release date, is being produced by Black Bear – who also worked with Sweeney on the pregnant nun horror Immaculate earlier this year.