One of Emmy-winning Ellen DeGeneres' most famous dance partners is returning for a surprise twirl that's sure to make her head spin: that's right, Justin Timberlake will be making a prank cameo on an upcoming "Ellen" show.

"There's a rule around here that nobody surprises me," Ellen tells Justin when he arrives. But the quick-witted Timberlake responds, "Well, I don't work here, so that doesn't apply to me."

From Janet to Missy to Britney, heartthrob Justin is just one of a long list of stars who have been teaching Ellen to dance on TV. But Ellen confided her favorite dancer to us at the recent Creative Emmy Awards: "Usher was on recently and he was pretty good. And Justin Timberlake's a pretty good dancer."

And as well as sweeping Ellen off her feet, Timberlake tells her he's also been giving sweetheart Cameron Diaz a few dance lessons.

"Cameron said the other day you laugh at her and say 'don't do that again,'" Ellen tells Justin while discussing his girlfriend's dance moves.

"It's just so she doesn't get a big head, that's all," Timberlake answers.

And you can see more of Justin and Ellen kicking up their heels when the episode airs next month.