Kelly Clarkson teams with Christina Aguilera

One week before her album hits stores (April 15), last season’s ”American Idol” champ Kelly Clarkson has finally picked the first single — and its hard R&B sound may shock fans who embraced the mellow ”A Moment Like This.” ”Miss Independent” begins with Clarkson singing in a throaty moan over a bangin’ hip-hop beat, then bursts into a power-chord-propelled, disco-diva chorus that’s not unlike Britney Spears’ ”Stronger.” ”What is the feelin’ takin’ over/ Thinking no one could open the door,” Kelly belts. ”Surprise — It’s time to feel what’s real.”

Clarkson tells EW.com that she had an unexpected writing partner on ”Miss Independent”: Christina Aguilera, whom she’s never met. ”I was working with my producer, Rhett Lawrence, and he was playing the ‘Miss Independent’ beat and I was like, ‘That’s hot.’ And he was like, ‘It’s already kind of a song,”’ Clarkson says. It turned out that Lawrence and Aguilera had toyed with ”Miss Independent” as a track for her last album, ‘”Stripped,” but never finished it. Some tinkering time later, Clarkson, Lawrence, and Aguilera now share writing credit for the song, according to a representative for both artists’ label, RCA.

Why was the single released unusually close to the album’s street date? The CD wasn’t finished until last month (recording didn’t start until February), and then Clarkson and her team, which now includes industry vet Clive Davis, had trouble picking a lead-off track. ”We had too many good ones we were trying to choose from,” Clarkson says. Among the album’s other songs is ”You Thought Wrong,” on which Kelly duets with former ”Idol” contestant Tamyra Gray. But that’s it for ”Idol” finalist guest appearances on the disc. Sorry, Ryan Starr.