After seeing a new promo, many fans are wondering if Derek and Addison really kiss in next week's crossover event, in which the worlds of Grey's Anatomy and Private Practice collide for the first time since 2007's "backdoor pilot" that spawned the spinoff?

Well, worried Grey's Anatomy fans can officially step away from the ledge, as E! Online cites a source saying Addison and Derek DO NOT kiss despite the misleading promo below.

The alleged kiss is about 18 seconds in. Stupid Shonda and her mind games.

[video url="http://www.tvfanatic.com/videos/beat-your-heart-out-promo-3/" title="Beat Your Heart Out Promo #3"] [/video]

Despite appearances, the source says of Addison and Derek: "No, there's no kiss. They are still just friends. There is no romance between them in the crossover episode."

Instead, the romance comes from Derek plotting his proposal to Meredith, and Lexie and Mark going public ... and possible flirtations betwen Callie and Arizona.

Check out our photo gallery for some cool pictures from the episode, which promises more than a little drama and intrigue! Sneak preview(s) to come shortly...

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.