When Kellie Pickler had the chance to perform with Kenny Rogers last year on Nashville's historic Ryman stage, the decision was easy.

"That was such a surreal moment for me," she tells Billboard. "I will never forget the invite. He was going to do a benefit for Cumberland Heights at the Ryman. He had recorded 'Someone Somewhere Tonight,' then I recorded it last year for 'The Woman I Am.' He loved what I did with it, and of course, who doesn't love what he does? It just made sense for us to come together and to perform the song as a duet."

Pickler and Rogers performed 'Someone Somewhere Tonight' in September 2013 as part of the 16th annual Concert for Cumberland Heights, with proceeds from the event going to help the organization offer young people residential, primary and extended care treatment as well as outpatient services.

"I was so nervous. I will never forget it," Pickler says of the performance. "I remember watching him and Dolly sing 'Islands In The Stream,' so I told myself that I was going to pretend I was Dolly for a second. It was a special moment, for sure -- especially there. There's no bigger stage in country music than the Ryman."