Whether it's crossing blades with Antonio Banderas or dangling from skyscrapers alongside Sean Connery, Catherine Zeta-Jones has never been one to shy away from physically demanding roles. But even she experienced a momentary twinge of doubt when it came time to lace up her dance shoes for the movie-musical Chicago (opening Friday).

"It was like looking up Mount Everest knowing you have to come down the other side," recalls Zeta-Jones of the intensive training she and the rest of the cast (which includes Renée Zellweger and Richard Gere) had to undergo before shooting the long-awaited film adaptation of the popular Broadway musical.

The actress did have a leg up on her co-stars in one respect: This wasn't the first time she played a hoofer. In fact, Zeta-Jones' career originated in musical theater. As a child performer, she appeared in several shows including Annie and Bugsy Malone. Her big break came at the age of 17 when she landed the lead role in the West End production of 42nd Street. After that, she traded the stage for the screen. "I hung up my dance shoes and never thought for one minute that, at 33, I'd be putting them back on and trying to do the splits again."

Surprisingly, re-learning those old moves didn't prove as difficult as she expected. "The hardest thing for me was the stamina," says Michael Douglas's other half. "I had some really physical things to do." Her solo numbers proved particularly challenging. "They couldn't cut away to anybody else. It was just me alone for two days, throwing myself on chairs and being bashed up and bruised." That dedication impressed her co-stars though. "I had no idea Catherine could sing and dance like that," marvels Queen Latifah, who plays jailhouse boss Mama Morton. "Just watching her belt out [her songs] I was like, 'Holla!'"

Next up for Zeta-Jones is the decidedly less-strenuous Coen brothers movie, Intolerable Cruelty, due out in 2003. But she says she's definitely ready to show off her moves again, should the opportunity arise. "I'd really like to do a rock musical," she offers. "I don't see myself doing Oklahoma."