Cameron Diaz and Diddy Are Hooking Up!

Credit: Slaven Vlasic/Getty; D Dipasupil/FilmMagic

A-Rod who?

She may have struck out with Alex Rodriguez, but Cameron Diaz isn't throwing in the towel on men.

The actress, 39, has reunited with Sean "Diddy" Combs, her off-and-on hookup since 2008, when Combs pursued her during Oscars week, a source tells Us Weekly.

"Since then, when she's single, she'll booty call him," adds another insider.

And now, they've gone public: Nuzzling in a booth at NYC's Catch on Oct. 24, the two were "inseparable -- they had their hands all over each other," an eyewitness tells Us.

Two weeks later, at a Nov. 11 lunch at Scarpetta in Beverly Hills, they were "making out, acting romantic," says a source. (Reps for both stars say Diaz and Combs, 42, are "just friends" and meeting to discuss a possible comedy film project.)

One hitch: Combs is still dating his model girlfriend of three years, Cassie, 25. Says a friend, "Diddy's single whenever there's a better offer on the table!"