Jennifer Lopez & Bradley Cooper: Getting Serious!

When Jennifer Lopez and Bradley Cooper dined at high-end eatery Per Se in NYC last month, they insisted it was, to quote The Godfater, "strictly business." Guess that depends on how you define "business": In the wee hours of Oct. 15, the pair was seen in Bradley's Mercedes — and sources confirm the Hangover star was driving J.Lo home to her Calabasas, Calif., estate after a steamy weekend at his Venice Beach pad.

"They were singing to the radio," an eyewitness tells OK!, "laughing having a good time, like they've been hooking up for a while. They were so relaxed and natural!"

Indeed, sources close to J.Lo, 42, and Bradley, 36, say a romance is heating up.

"They have tremendous chemistry, and Bradley's totally smitten with her," an insider tells OK!. Adds another, "They can't keep their hands off each other."

J.Lo, of course, recently split with  husband Marc Anthony, 42, while Bradly broke up with his last serious girlfriend, Renée Zellweger, 42, in March. "Jennifer is so different from Renée," the insider adds. "But Bradley loves exotic, dark women — and loves that she's powerful and strong-willed."

FOR MORE ON J.LO & BRADLEY'S BUDDING ROMANCE, PICK UP THIS WEEK'S ISSUE OF OK! — ON SALE EVERYWHERE NOW!