A Formal Theme Doesn't Keep Sexy Away

The theme for tonight's Costume Institute Gala at the Metropolitan Museum of Art might've allowed less room for full-on sexbomb outfits than last year's anything-goes punk approach, but don't worry: where there's a red carpet, there are bound to be some sultry numbers. Whether it was a low-cut front or a high (high) leg slit, ladies like Lea Michele, Chrissy Teigen, and Nicole Richie had sexy on tap. Scroll down to see all the best.

Kate Upton at the Costume Institute Ball
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Kate Upton at the Costume Institute Ball

A semisheer Dolce & Gabbana dress with a corset and underwire bustier made sure to flaunt Kate Upton's famous curves.

Beyoncé at the Costume Institute Ball
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Beyoncé at the Costume Institute Ball

Beyoncé went bold in a Givenchy Haute Couture mousseline dress embroidered with a mix of crystals, stones, and studs. Under it, she wore a bodysuit and fishnets.

Cara Delevingne at the Costume Institute Ball
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Cara Delevingne at the Costume Institute Ball

What ball gown? Cara Delevingne showed that she plays by her own rules in a two-piece set made up of an intricate crop top and skinny white pants.

Kim Kardashian at the Costume Institute Ball
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Kim Kardashian at the Costume Institute Ball

While we've certainly seen sexier from Kim Kardashian, the high slit of her midnight blue dress rose nearly to waist level, ensuring things maintained a certain amount of steaminess.

Naomi Watts at the Costume Institute Ball
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Naomi Watts at the Costume Institute Ball

The ombre hue of Naomi Watts's custom Givenchy Haute Couture dress was gorgeous, but what we couldn't take our eyes off was the sheer skirt that let flaunted her stems.

Rihanna at the Costume Institute Ball
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Rihanna at the Costume Institute Ball

Rihanna's pure white look was far from angelic, thanks to the cropped top that fell right below her bust (allowing a tattoo to peek through!).

Chrissy Teigen at the Costume Institute Ball
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Chrissy Teigen at the Costume Institute Ball

Chrissy Teigen wore a one-of-a-kind Ralph Lauren Collection halter dress covered with Swarovski crystals and organza ruffles. For accessories, she picked Lorraine Schwartz earrings.

Dree Hemingway at the Costume Institute Ball
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Dree Hemingway at the Costume Institute Ball

Dree Hemingway had a retro moment in a Proenza Schouler dress that hit at midcalf, white Rupert Sanderson pumps, and Harry Winston earrings.

Georgia May Jagger at the Costume Institute Ball
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Georgia May Jagger at the Costume Institute Ball

Georgia May Jagger went for it up top and on bottom with a neckline that dipped to her navel and a high slit on the leg. For shoes, she picked suede Sergio Rossi heels.

Lea Michele at the Costume Institute Ball
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Lea Michele at the Costume Institute Ball

Lea Michele sizzled in a backless golden Altuzarra dress and Lorraine Schwartz accessories.

Nicole Richie at the Costume Institute Ball
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Nicole Richie at the Costume Institute Ball

Nicole Richie skipped volume in favor of a custom-dyed velvet Donna Karan Atelier gown, worn with Christian Louboutin shoes, a Zagliani clutch, and custom diamond House of Harlow jewelry (including ear cuffs!).

Zoe Saldana at the Costume Institute Ball
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Zoe Saldana at the Costume Institute Ball

The neckline of Zoe Saldana's custom black cashmere Michael Kors bodysuit went low enough to show off some cleavage. Atop it, she picked a black and white lace taffeta skirt, also by the label.

Olivia Munn at the Costume Institute Ball
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Olivia Munn at the Costume Institute Ball

Even with long sleeves and a floor-length hem, Olivia Munn couldn't help but sizzle in her dress. For jewels, she picked Fred Leighton.

Zoe Kravitz at the Costume Institute Ball
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Zoe Kravitz at the Costume Institute Ball

In a slip of a dress, Zoe Kravitz's silk Topshop number was definitely more sensual than the voluminous ball gowns we spotted.