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Debra Messing is moving on.

The actress, 43, who announced exclusively to Us Weekly on Dec. 20 that she and her producer husband of 10 years Daniel Zelman had split earlier this year, has already found love again.

An insider tells Us that Messing has fallen for actor Will Chase, her costar (their characters share a romantic past!) on the NBC musical drama Smash.

"Debra and Will have been together for about six weeks," says the insider. "She is completely smitten with him." And while the relationship is still new, it's already serious.

According to the source, Chase 41, has left his wife of two years, stage actress Stephanie Gibson (Chase has two tween daughters, Gracie and Daisy, from a previous marriage).

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"Will didn't break up Debra and Daniel. It was over before she met Will," the source clarifies of Messing and Zelman, 44, who amicably share son Roman, 7, and will "continue to live together with their son, then gradually transition into a new living situation," they explained to Us in a statement.