When Keith Urban went looking for somebody to collaborate on his song "Drop Top," off his upcoming album Graffiti U, he had something very specific in mind.

"I said, 'Whoever the girl is, she's gotta have the right voice, she's gotta have the right attitude, she's gotta have swagger,'" Urban tells Taste of Country. "Legit, not faux swagger. The real deal."

The country star found what he was looking for in up-and-comer Kassi Ashton. Not only did she hit the "swagger" button on the head, but Urban says her individual style is unlike anybody out there. One of the Boot's New Artists to Watch, Ashton is clearly carving out her own niche in the country music world; when asked to compare Ashton to a similar artist, Urban says he can't find a parallel.

"She reminds me of Kassi Ashton," Urban says. "She's such a unique, original creature. I don't know who her influences are, but they sound somewhere between Tammy Wynette and Beyonce. It's so extraordinarily unique."

"Drop Top" tells the story of a group of girlfriends en route to Coachella in a Jeep. The song is one of several collaborations on Graffiti U, including Urban's duet with singer-songwriter Julia Michaels on "Coming Home," which has been out as a single since late March.

Ashton recently signed with UMG Nashville and is teasing the upcoming release of her first full-length album, which will include the single "California, Missouri," a song about her hometown.

Graffiti U is due out on April 27.

Unforgettable Keith Urban Moments