Kate Upton didn't quite step out in her birthday suit -- but she came close.

The supermodel had an early birthday celebration at The Blond at 11 Howard Hotel in New York City on Wednesday night, ahead of her turning 24 on Friday. Upton bared her butt in a thong bodysuit that she wore under a sheer, star-embellished dress. While posing with her fiance, 33-year-old MLB pro Justin Verlander, the Sports Illustrated Swimsuit cover girl got cheeky with photographers and flashed her bum.

A photo posted by Kate Upton (@kateupton) on

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Bella Hadid and Nick Jonas also attended the birthday celebration, which included cake and tequila shots. "I'm so happy to have my friends and family with me today!" she posted to Instagram.

Upton has lots to celebrate this year! Last month, ET confirmed that the model got engaged to Verlander just as she was flashing her engagement ring on the Met Gala red carpet.

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Upton meeting her man while filming a commercial for MLB 2K12, the two reportedly started dating on-and-off for three years. "We're really happy right now and just continuing being happy,” she told ET in January.

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