Katy Perry and Kacey Musgraves

Pop princess Katy Perry and country music darling Kacey Musgraves grace the cover of this week's Billboard. The pairing isn't as random as you think: the singers are teaming up for an upcoming "Crossroads" special (June 13 on CMT), and in August Musgraves joins Perry's Prismatic world tour as opener. As Perry points out in the cover story, there's a kinship there that goes beyond their shared backgrounds as All-American girls from conservative worlds.

"I think [Kacey] straddles the line like I straddle the line of appropriateness and still maintaining a sexuality that is healthy and exciting," Perry says. "And it's not all about that. It's about sending inspiring and empowering messages and being a think-for-yourself type of woman."

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Go behind the scenes of Katy and Kacey's Billboard cover shoot in the exclusive video interview below, plus check out five things we learned about music's hottest tour coupling of the year.

WHY A KATY/KACEY PAIRING MAKES SENSE. "We're both very whimsical in our own ways, but I think at heart we're both songwriters," says Musgraves. For her part, Perry says she "instantly connected" with her country counterpart after hearing her debut single "Merry Go 'Round." "She struck a chord in me," she says. "I feel like we have the same eyes. Not in a physical sense, but in a way of perception."

KATY STALKED KACEY. After she heard "Merry Go 'Round" Perry did a little bit of ol' fashioned cyberstalking -- "as I do with everyone," she notes -- and reached out to Musgraves about teaming up. The songs they worked on didn't make the cut on "Prism," but a partnership was born. 

Katy Perry and Kacey Musgraves Take
America: Billboard Photo Shoot

WHAT YOU'LL HEAR ON THEIR CROSSROADS SPECIAL. Expect songs from each of Perry's three studio albums, encompassing her fun, inspirational and singer-songwriter selves. She'll also take a backseat during Musgraves' set. "You'll hear me doing a lot of background vocals… and a little of that country flair." Musgraves will bring a "storyteller vibe" to her set, which she admits won't have any "super-anthemic, firework-type songs." Hearing a reference to one of her biggest hits, Perry shot back, "are you making fun of my song?"

KATY HAS SEEN KACEY NAKED. "A couple times," Musgraves confirms. "And it won't be the last." They'll have plenty more chances for dressing-room exhibitionism when Kacey joins Katy's "Prismatic" tour in August.

AND EXPECT DUETS APLENTY ON TOUR. Kacey: "For me, you could just put all your songs in a hat and just grab any of them and I would fucking love to sing any of them." Perry reassured her that "we're doing that on tour." Musgraves says that "Teenage Dream" is "obviously the best pop song ever written." 

Return to Billboard.com on TUESDAY morning for the FULL cover story.