Should Brad Pitt (search) be worried -- or are Jennifer Aniston (search) and Matt LeBlanc (search) merely the best of "Friends"?

The sizzling sitcom stars raised eyebrows outside a Los Angeles eatery as LeBlanc pulled up in his silver Porsche and jumped into the arms of his sexy but very married former TV co-star.

Then, as startled witnesses watched, Jennifer and Matt launched into a tender kiss, as these exclusive photos show.

Next, Matt buried his face into Jennifer's gorgeous hair and the tender twosome snuggled in the bright California sunshine.

When the embrace ended, Jennifer made sure she got rid of the evidence, reaching up to wipe her lipstick off Matt's face. Then she playfully placed her hand over his mouth.

With their "kiss-toric" meet-and-greet out of the way, TV's Rachel and Joey strolled into the trendy Pane E Vino restaurant for lunch.

While they both looked oh so cozy, the delectable duo's pals insist they're nothing more than good friends who like to stay in touch.

The pair have been pals for a decade but they'll no longer be co-stars -- the final episode of "Friends" has filmed and will air May 6 on NBC.

Reps for both Jennifer and Matt did not return calls.

LeBlanc, who has packed on a few pounds over the years, probably wouldn't want to mess with Pitt now, anyway -- Brad's in kick-ass muscleman shape after quitting smoking and bulking up for his big sword-and-sandal flick "Troy."

Not that Pitt can complain one iota about the tender kiss his squeeze was caught in with LeBlanc.

In recent weeks, hunky blond heartthrob Brad was caught holding hands with luscious Angelina Jolie on the set of their new flick "Mr. and Mrs. Smith" -- an eye-popping sight that had Hollywood tongues wagging.