Jewel, Michelle Branch, Kelly Clarkson, and Nelly: the stars are in Vegas, and only "Extra" is inside rehearsals for Monday night's Radio Music Awards.

And we've already found out some "Extra" secrets. Nelly says, "Yeah, Diddy is involved; we were hoping to keep that a surprise."

Michelle Branch says, "I don't have as much fun as other people." The 20-year-old is still too young to hit up the casinos. She says, "I just skate around and drink soda and play in the arcades."

Jewell says she is too busy for fun. She says, "I'm always gigging when I'm here."

And Kelly Clarkson says she is simply star struck. She says, "I'm pretty pumped about seeing Beyoncé and Avril Lavigne."

And hosting the big event is "American Idol's" Ryan Seacrest and Brooke Burns—a pair that used to date. Burns has since been spotted with Bruce Willis, but joined Seacrest for a behind-the-scenes tour of the gift room at the Aladdin hotel.

And you can catch all of the RMA stars Monday night at 9 p.m. on NBC.