Looking good is the best revenge -- just ask Renee Zellweger.

Days after splitting with her boyfriend of nearly two years, Bradley Cooper, the 41-year-old actress put her best foot forward when she attended a pal's low-key birthday bash at NYC's La Esquina restaurant Saturday.

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"She wore a skin-tight black dress and amazing lace-up shoes," an eyewitness tells UsMagazine.com. "She looked smokin' hot."

And people certainly noticed. "At one point, three waiters came up to see if the table needed anything because they wanted to check out Renee."

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Though Us broke the news of her split just one day earlier, the Oscar-winning actress showed no signs of heartbreak during the outing. (She and Cooper, 36, began dating in July 2009 after meeting on the set of the thriller Case 39 four years earlier).

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"She tried to make it work, but in the end it was too hard," a Zellweger insider told Us. "Her friends feel bad it ended, but she's okay."

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