The show-biz fates are a fickle lot.

And few know it better than Jennifer Hudson.

One minute, you are facing the nightmarish Simon Cowell, that snidely tongue-lasher of an "American Idol" judge, as he verbally shreds your disaster of a shocking-pink ensemble and announces that you are "out of your league" on national TV.

The next, you're nominated for a Golden Globe award, and there's Oscar buzz about your debut in one of the year's most anticipated films, "Dreamgirls." The snazzy big-screen version of the 1981 Broadway musical, winner of six Tonys, about a Supremes-style '60s girl group, will open in some cities on Christmas Day and goes nationwide in January.

Told that audiences are breaking into applause during the decadespanning saga that co-stars Beyoncé Knowles, Jamie Foxx and Eddie Murphy, she is elated.

"I had a dream last night that they're applauding at the movie," says Hudson, 25, tastefully attired in a flouncy green frock over a black T-shirt, adorned with just enough gold jewelry.

"And they do clap," she says with an infectious laugh.

And after learning that she was nominated for a Golden Globe, Hudson told an "ET" interviewer that she "started screaming and crying. It was just overwhelming. I've never experienced these many emotions in one moment in my life."

What this "Idol" reject isn't mentioning is that her assured and heartbreakingly authentic performance is the reason for most of the noise.

The vocal cyclone of a Cinderella from the South Side of Chicago with a gospel-bred multi-octave range has managed to step into a much-coveted movie role that has proved to be a perfect fit.

Like her character, the hefty, haughty and highly gifted Effie Melody White, this healthy-sized belter (she gained 20 pounds for the movie, and lost 25 — and that is it, she insists) defies the image of a svelte pop songstress while proving she can succeed on her own terms after being rudely shoved out of the spotlight by "Idol" voters in 2004.

At the New York premiere, a standing ovation — an event as rare in movie theaters as clean floors — greeted her rafterrattling rendition of the Mount Everest of show tunes, "And I Am Telling You (I'm Not Going)," a five-minute explosion of desperation, despair and determination.

"It takes your head off," says Foxx, who plays Effie's manager and boyfriend, Curtis Taylor Jr. and takes the brunt of Hudson's gale-force fury in the number after he banishes her difficult diva from the group and his bed. "She does a fantastic job with the acting and then, all of a sudden, she's singing that song. It's beautiful. It was hard not to cry and double up with emotions."

Or as Henry Krieger, who wrote the music for the original score with the late lyricist Tom Eyen and contributes four new songs to the movie, says of this star-on-the-verge: "People have gone cuckoo for her and I have, too. She is completely beguiling."

THE ONE TO BEAT

Hudson already is the belle of the Oscar season ball, as prognosticators have her pegged as the one to beat in the supporting-actress category. The National Board of Review, in a likely sign of more trophies to come, has already handed her a breakthrough-performance honor. The Las Vegas Film Critics Society and the African-American Film Critics Association also named her best supporting actress.

She also just signed a recording contract with super producer Clive Davis and his J Records label, home to Aretha Franklin, Barry Manilow and, oddly enough, all the "Idol" winners and runners-up.

And this dream-come-true girl, who began singing in churches at age 7 and worked as a Disney cruise-ship entertainer, is inspiring critical hosannas as well.

The nation's cultural curator, Oprah Winfrey, pronounced her performance "a religious experience."

Peter Travers in Rolling Stone gushed, "She can act. She can nail a laugh with the sassy curl of her lip. She can break your heart by letting her eyes show how she hurts. And she can sing until the roof comes off the multiplex."

Newsweek simply declared, "When she's center stage, 'Dreamgirls' is movie musical heaven."

Hudson even managed to impress Knowles, the R&B queen who leaves her "Pink Panther" and "Austin Powers" comedy comfort zone for nuanced drama as Deena Jones, the beauteous, slender and light-skinned Dream and Diana Ross stand-in who upstages the less-mainstream Effie when she takes over as lead.

"When I told people I was doing this movie, they were so happy for me," says the real-life veteran of girl-group wars after her reign in Destiny's Child.

"But they all wanted to know who was Effie and who was going to sing this song, "And I Am Telling You." Jennifer had so much pressure. Never doing an album before, never doing a movie before. And she pulled it off. She gave you chills and made you want to cry. We were all scared together and we all learned together, and I feel like a big sister when I watch her. I see that people know she is a star."

MODEST, HONEST, ENTHUSIASTIC

The rookie, who beat 782 other hopefuls (including the winner of her "Idol" season, Fantasia Barrino) to play Effie, accepts such profuse praise with genuine modesty and honest enthusiasm that speaks well of her upbringing, if not her strong sense of self.

"All I wanted to do was to be part of the movie and not disappoint," Hudson says. "I feel honored — and, like, wow. It was last year at almost this time that I was cast. But to go from that to all of this? I never dreamed this up. That I missed."

If director and writer Bill Condon, who scripted Hollywood's last big movie musical success, 2002's "Chicago," hadn't spied a certain spark during the audition process, Hudson may have missed her breakthrough completely.

When the field of would-be Effies was narrowed to 20, informal screen tests were done.

"Bill had called in the middle of her test in New York and said, 'There's something here. I'm very excited. There's something here,' " recalls producer Laurence Mark. "But for some reason, when we all saw the test, we couldn't quite see it ourselves."

With little time to spare, he persuaded Condon to trust his instincts, and they brought Hudson to L.A. so the director could work with her. She rose to the occasion.

"In the second test," Mark says, "she killed."