See Steven Tyler Join the Cadillac Three for 'Sweet Emotion'

Aerosmith legend was the country trio's big encore surprise at their sold-out Nashville show

Southern rockers the Cadillac Three became the Cadillac Four, temporarily, with the addition of their Big Machine Records labelmate, Steven Tyler, during a sold-out show at Nashville's Cannery Ballroom Saturday night. Taking the stage with the band, Tyler unveiled a special handmade T-shirt for the occasion, with the number four written on it. After tossing the shirt into the crowd, the iconic rocker led the band through a fiery version of Aerosmith's "Sweet Emotion."

In spite of  Tyler's choice of a tune from his earliest days as a rock god, he's kicking his country-music career into overdrive. In July, he released the video for his first country single, "Love Is Your Name," and next week he and his country outfit, Loving Mary, will headline the first-ever Pilgrimage Festival, taking place in Franklin, Tennessee, just south of Nashville, on September 26th and 27th. (Willie Nelson, Sheryl Crow, Punch Brothers and reggae icon Jimmy Cliff are among the other acts performing.)

Tyler has been writing with some of Nashville's most accomplished songwriters over the past year, including Cadillac Three lead singer Jaren Johnston, and will eventually release a full-length country LP. The 67-year-old musician, who recently wrapped up an Aerosmith tour, appreciates the directness of country music and its artists who are adding dimensions to the genre.

"Country songs really spell out what's on a guy's mind in no uncertain terms. Rock & roll can be a little more aloof," Tyler tells Rolling Stone Country. "But country is changing. Jaren Johnston and the Cadillac Three and Florida Georgia Line are proving that you can go any which way. Modern country might add a little a cappella or raps or heavier beats. God knows Brad Paisley plays guitar like a motherfucker. I think country is the new rock & roll — everyone is trying to stretch out."

Meanwhile, the Cadillac Three continue to hit the road with shows this week in California and Virginia. See more of the group's tour dates here.