The buildup to Leona Lewis‘ stateside debut has been so great that you half expect her to be surrounded by heavenly angels when she appears.

Backed by music mogul Clive Davis, the budding British diva already has drawn comparisons to Mariah Carey and Whitney Houston for her booming voice. Oprah Winfrey fawned over her talents on a recent show.

She even managed to win over cranky “American Idol” judge Simon Cowell when she won “The X Factor,” the British version of “Idol.”

Cowell and Davis produced her debut album, “Spirit,” which was released in the U.S. last week.

Last month, she topped the Billboard Hot 100 chart with her first single, “Bleeding Love” – the first time a British woman has done so in 21 years.

“It’s quite scary,” Lewis, 22, says of the Houston-Carey comparisons. “Personally I’ve got a lot of hard work to do.”

Carey and Houston debuted when dramatic power ballads ruled radio – which is no longer the case. That’s why “Spirit” includes a mixture of midtempo songs and ballads, like Roberta Flack‘s classic “The First Time Ever I Saw Your Face.”

The daughter of a Guyanese part-time DJ and a Welsh ballet teacher, Lewis grew up exposed to a variety of genres.

She got the performing bug early, appearing in local talent shows as a child and attending a performing arts school. But in her early teens, it was opera, not pop, that enthralled her.

“My training is kind of classical, so I’ve done a lot of opera, and I was very interested in Leontyne Price,” Lewis says her in sweet, shy-sounding voice.

“As I got older and more into, like, contemporary music and all that kind of jazz, soul and blues … I kind of found myself shifting toward that.”

At 17, the London native decided to pursue music full-time, leaving school in hopes of realizing her dreams. Early setbacks left her discouraged.

“I was quite frustrated because I really wanted to be able to make a living from it,” she says.

“I’d been going into the studio and writing and working with different producers and I’d be auditioning for different shows … it was quite a struggle.”

Her break came when she auditioned for “The X Factor,” which she won in December 2006.

While “Spirit” was an instant best-seller last year in Britain, Lewis is quick to downplay expectations for her U.S. debut.

“You know what? To just get the chance to come over and share my music together is just amazing to me,” she says.

“I don’t know how it’s going to do, I don’t know how people are going to receive it, I can just hope that it will be received well. But to just get this chance? It’s incredible.”

The birthday bunch

Actor Lyle Waggoner (“The Carol Burnett Show”) is 73. Actor Paul Sorvino is 69. Actor Tony Dow (“Leave It To Beaver”) is 63. Musician Al Green is 62. Actor Ron Perlman is 58. Drummer/bandleader Max Weinberg is 57. Actress Saundra Santiago (“Miami Vice”) is 51. Actress-comedian Caroline Rhea is 44. Actor Ricky Schroder is 38. Singer Nellie McKay is 26.