LOS ANGELES—The invitation said 'One Night Only.' But for some people attending the recent 'Dreamgirls' movie press event at the Orpheum Theatre in downtown L.A., that one night and one number—“Step into the Bad Side”—performed by Beyonce Knowles, Jennifer Hudson and Anika Noni Rose, was not enough.

That's because anticipation for the filmed version of this Tony Award-winning Broadway musical has been mounting for more than two decades. The original play, which made its White Way debut in 1981, was reportedly based on the juicy true-life drama that split up The Supremes in the late 60s.

That was a rather easy connection to make considering the play chronicled the rise and fall of a '60s girl group that fell apart after egos clashed when the group was renamed to reflect the rising stardom of the lead singer. The Supremes, despite the objections of Florence Ballard, transitioned into Diana Ross & The Supremes while the fictional Dreams were reconfigured into Deena Jones & The Dreams.

The only difference between the fictional and factual account is that The Dreams, despite Effie's defection, eventually found their way back to each other -- if only for one night. The original Supremes, however, weren't so fortunate. Ballard, the model for the Effie character (Hudson), was fired in 1967 and replaced with Cindy Birdsong. Ballard died broke in 1976, six years after Ross bolted to pursue her own solo career.

The play made stars of Sheryl Lee Ralph, Jennifer Holliday and Loretta Devine, but the film will feature a star-studded cast that includes Knowles as Deena, Jamie Foxx as Dreams manager Curtis Taylor Jr. and Eddie Murphy in the role of singer James "Thunder" Early.

Although Knowles, the former lead singer of Destiny’s Child, knows all about defections and bruised egos when it comes to girl groups, she’s no real-life Deena. She’s just a girl who believes that she was born to play this role. "I know I’m supposed to be Deena," the nine-time Grammy winner says. "I know that and I know I’m going to do a great job at it. And I know that I’ve been hearing about this 'Dreamgirls' since I was 15. I know about every little detail from her beginning to her end. I have been a student of it."

According to Foxx, Knowles has been working her butt off. That might explain her new svelte figure.

"Dreamgirls is going to knock your wig off," Foxx says. "Beyonce is so focused that she doesn’t even laugh at any of my jokes between takes. She’s just that focused."

That's understandable because even though this is Knowles' fourth feature film, it's her first lead role. And it's a pretty safe bet that she doesn’t want her dream project to turn into a box office nightmare.

Judging by what we saw on stage at the Orpheum the likelihood of that happening is slim to none. From the wigs to the stilettos, the celluloid Dreams will be every bit as impressive and celebrated as their stage counterparts on any given night.