If her older brother, Andrew, had had his way, Renée Zellweger probably wouldn't be headlining Miramax's eagerly anticipated film adaptation of the classic Broadway musical, Chicago (opening Dec. 27). "He always used to yell 'Shut up!' any time I tried to do a rendition of a Beatles song," Zellweger recalls to TV Guide Online, laughing. "I was told that I couldn't sing in the house. Anything to abuse his little sister; it was his job and he did a very good job."

Fast-forward 10 years later and Zellweger is knocking 'em dead as Chicago's merry murderess, Roxie Hart — a role that just earned her a Golden Globe nomination for best actress in a musical or comedy. How did a performer with no formal vocal or dance training wind up landing one of Hollywood's most coveted parts? Two words: Rob Marshall, the film's director.

"I needed to find a performer with that amazing range from drama to humor, from vulnerability to likeability," Marshall explains. "I found someone like that [with Renée], but I didn't know if she could sing or dance. When I found out she could, that was the 'Eureka!' moment." Marshall's enthusiasm helped clear up any of Zellweger's apprehensions. "Rob was so passionate that if he said I could do it, I'll do it. It didn't matter to me. I wanted to spend six months of my life with that man."

Of course, much of that time was spent in training. "We were very busy at the Rob Marshall School of Chicago," Zellweger says. "It really was like school. We would have different periods. There was singing, there was dance, you'd go to a group number, you'd go have a solo, you'd go have a little lunch and then come back together in the afternoon to do dialogue."

As for Andrew, Zellweger confesses that he has yet to see his little sister's latest career move. Chuckles the erstwhile Bridget Jones: "He's far too busy to worry about my silly life."