Michelle Williams, Jason Segel Heating Up

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Michelle Williams and new beau, funny guy Jason Segal, have taken their romance public.

After being spotted together several times on the streets of New York City, the pair were sweetly affectionate at Wednesday's premiere of Segal's new film, "The Five-Year Engagement" at the Tribeca Film Festival.

According to People magazine, as the screening ended, Segal gave Williams a kiss on the cheek as she rose to leave. Later, when the "My Week With Marilyn" star caught up with Segel at the after-party at the Museum of Modern Art, he held her hand and whispered in her ear, the magazine reported.

"Jason would put his arms around her waist and they gave each other a few sweet pecks - they definitely seemed to have a physical chemistry," an onlooker told Us Weekly. "Every actor in there was so enamored by the couple!"

Segel, 32, recently commented on his surprise relationship Williams, 31, whose famous ex, the late Heath Ledger, is the father of her 6-year-old daughter Matilda.

"I think we would just very much like to be happy. That's all I'm going to say about it," the actor told Extra earlier this week.

Last week, he let his technology do the talking last week, when he revealed that he has photos of Williams taped to the back of his iPhone.