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What was Jessica Biel doing while ex-boyfriend Justin Timberlake jokingly fondled Mila Kunis on national TV? She was clinging tightly to the back of Gerard Butler.

Two months after hookup rumors first surfaced on the Shreveport, La., set of "Playing the Field," co-stars Biel, 29, and Butler, 41, were photographed this weekend taking a motorcycle ride in Malibu along the scenic Pacific Coast Highway.

The starlet's two-wheeled spin on the back of the Scottish actor's Harley (with both in leather jackets and matching helmets) has already reignited simmering romance rumblings, which began to heat up in April.

(Please feel free to make the obligatory "the butler did it"` joke here so we won't have to. Thanks.)

Seems the pair connected even before shooting began, with a run-of-the-mill group meal turning into an anthropological observation on the mating rituals of the rich and famous.

"He knows he looks good," a snitch tells People of seeing Jessica and Gerry cozy up at a Japanese joint during a kick-off dinner with the cast and crew. "If I were her, I'd hook up with him. She looks good, too, and she knew she looked good, swinging her hips around."

Reckons the onlooker, "They looked like a couple. They were having a good time."

Pipes in another source, "Gerry has a large personality, and everyone, including Jessica, gets caught up in his world. I think they enjoyed each other's company. It can be hard working on a movie, trying to establish a new routine, and it helps when you have someone with you to make you feel more normal."

So, are they making each other feel normal now that the cameras have stopped rolling? Apparently only as pals.

"They're just friends," Butler's rep assures Wonderwall. Biel's rep also tells us it's a "just friends" situation.

And indeed, Biel was nowhere to be seen on Monday, when the actor was snapped surfing in Maui, his back-to-chiseled six-pack on display.

Meanwhile, Jessica doesn't appear to be harboring any ill will toward Timberlake, whom she "mutually" decided to part ways with in March after four years of togetherness.

E! News reports the exes bumped into each other at a friend's party on Thursday but avoided any awkwardness.

"There was no PDA, but they were talking to each other for awhile," says a spy. "They ate and sat next to each other. They hugged goodbye and kissed each other on the cheek."

In a recent Vanity Fair interview, Justin, who is currently rumored to be seeing Ashley Olsen, said Jessica was "the single-handedly most significant person in my life. In my 30 years, she is the most special person, okay?"


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