In what is bound to be one of the most talked-about performances of the 2015 ACM Awards, Rascal Flatts took the stage with Christina Aguilera during the live broadcast to perform part of Aguilera's current single, "Shotgun," along with the Flatts' current single, “Riot."

Aguilera took the stage first, performing "Shotgun" with Joe Don Rooney on guitar, before Gary LeVox came out on stage to sing with the her. They then launched into "Riot" with a full band, and Aguilera took a turn on the second verse, with the two harmonizing on the chorus.

“When you make a list of people you want to collaborate with, over the years, that list gets shorter,” band member Jay DeMarcus notes. “Christina was one of those names that’s always been at the top of the list, but we’d never had the chance to work with her.”

Aguilera is becoming a familiar face among country music fans. She is currently starring in the ABC drama Nashville, as the fictional pop star Jade St. John, who aspires to develop a career in country music instead.

Rascal Flatts were nominated for an ACM Award for Vocal Group of the Year tonight, with the trophy going to Little Big Town. Still, it marks their first nod since 2012, which, for the trio, was a sign that they were still moving in the right direction.

“It really means the absolute world to us,” LeVox said. “It felt so good to be nominated again. Not that we went anywhere. We’ve been hopping like we have every year. But you miss what you don’t have."

“A few years ago, I stopped waking up and looking at the nominations, because it had just become so normal for us to not be in there anymore,” DeMarcus adds. “It was a great ... to have so many great e-mails and phone calls from friends, from people that were pulling for us to be back in there. I was really speechless."

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