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All grown up! Many remember Alexa Ray Joel as Billy Joel and Christie Brinkley's adorable, grinning little girl, but the now-28-year-old singer looked surprisingly transformed on April 1.

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Performing at Cafe Carlyle in New York, Joel posed in a cleavage-baring, lace-covered corset and long, printed skirt.

Her angular jawline, flawless skin, and sultry pout were a far cry from the beaming preteen many remember. But that doesn't mean she's had work done to look this glamorous. According to her rep, the musician's new look is simply, well, maturity.

"Alexa has never had any plastic surgery other than a rhinoplasty, which she has admitted to," the rep tells Us. "She's simply matured into a beautiful young woman."

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Alexa is the daughter of Joel, 64, and model Brinkley, 60. She has been performing since age 19 when she first put together a band and played local shows in New Jersey. Her performance in New York last night was sold out.

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"It was a pristine honor to grace a stage that has seen such legendary-greats as Bobby Short, Woody Allen, and -- my personal fave -- Eartha Kitt," she wrote on Instagram. "This 2-week long showcase (from April 1st-12th) is my very own handmade love-letter to New York, from start to finish; every minute-element of the performance, from my reinterpreted covers, to my original-material, to every note on the cello- was arranged wholly by me- And I can truly say that this is the first performance-run I've ever done where every beat of the show is coming entirely from the deepest dwellings of my heart and mind."


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