Oh, what could've been!

Justin Timberlake's love Jessica Biel unsuccessfully tried out for the lead part of Jamie -- which ultimately went to Mila Kunis -- in Friends With Benefits.

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"She was actually a huge fan of the project and screen-tested for it years ago," David Newman, one of the comedy's screenwriters, told the New York Post's Page Six at Monday's NYC premiere. Why was Biel, 29, rejected for the role opposite Timberlake, 30?

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"We're not the director," Newman retorted. "She's great and adorable -- smoking hot!"

He added simply of Kunis, 27: "Mila was fated for the role."

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While Biel lost on out on that particular part, she may be faring a little better with her real-life man. Although she and Timberlake announced the end of their on-and-off four-year romance in March, they are "quietly seeing each other again," a source recently told Us Weekly. "[They] decided to give it another shot."

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