Earlier this year Hayes spoke with Radio.com about his Monroe duet, "What You Gonna Do," which appears on the extended edition of his debut album, Hunter Hayes Encore. He cited the Pistol Annies member as having a "timeless, iconic sound."

"I recorded that song 20 times," he said. "I was out of ideas and didn't know where else to go with it. I needed something else. Something to re-inspire it. I think she brought in exactly what I needed: a different perspective. There's something about the way she sings it that gives it a different meaning. It gives it a different texture and it reinvented the song."

Hayes and Monroe's tour kicks off tomorrow (October 10) in Knoxville, Tennessee and runs through December. The two have toured together before as a part of MTV's Artist to Watch series and performed a duet each night � something to expect from their upcoming tour.