Kane Brown had a surprise in store for fans who caught his CMA Fest set. The rising star brought out Lauren Alaina to sing with him on their recorded duet, "What Ifs."

After singing the first verse on his own, a big smile encroached on Brown's face as he looked side stage. Moments later, Alaina walked onto the Riverfront Stage. She was met with screams.

The longtime friends were at ease beside each other onstage as they sang harmony on the chorus and traded several verses on the song.

"What Ifs" is Brown's latest single off his major label debut, released late last year. The song was co-written by Brown, Matthew McGinn and Jordan Schmidt, and Brown recently released the music video, which was directed by P. R. Brown and produced by Steve Lamar. “What Ifs” was also the first music video to be filmed at the Inn at Newport Ranch on the North California coastline.

Alaina and Brown met as kids at their Georgia middle school, where they were in the same choir class.

“He was very, very shy,” Alaina tells People. “We were sitting in class one day and I heard him humming, and I was like, ‘Can you sing?’ And you said, ‘No, I don’t sing in front of people.’ And I was like, ‘Well, you’re going to today.’ He was even better than I thought he would be. When he started singing, I was like ‘Stop singing! I want to be the best singer in class.'”

Clearly, success found both of them.

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