During an appearance on Monday's episode of The Kelly Clarkson Show, the two superstar musicians performed a casual and heartfelt acoustic duet of Shelton's 2001 debut single, "Austin."
In a clip from the interview uploaded to YouTube, the 40-year-old American Idol alum said she'd like to duet the two-times platinum-certified hit single and asked Shelton, 46, to start playing the tune on his guitar. "I've never heard you sing on this show, so that's cool," he joked to Clarkson, who opens each episode of her NBC talk show by performing a new song cover as part of the Kellyoke segment.
As Shelton started strumming the song's opening guitar part, he exclaimed, "Holy crap, I played it!"
The Kelly Clarkson Show Blake Shelton and Kelly Clarkson
He sang the first verse, "She left without leavin' a number / Said she needed to clear her mind / He figured she'd gone back to Austin / 'Cause she talked about it all the time / It was almost a year before she called him up / Three rings and an answering machine is what she got."
Clarkson then harmonized with Shelton during the song's chorus: "If your callin' 'bout the car, I sold it / If this is Tuesday night, I'm bowlin' / If you've got somethin' to sell your wastin' your time, I'm not buyin' / If it's anybody else wait for the tone you know what to do / And P.S., if this is Austin, I still love you."
Following applause from the crowd, the "Since U Been Gone" singer-songwriter spoke to her love for the song. "It's so good," said Clarkson. "I know that Blake fans already know this, but you've gotta listen to the whole song, 'cause then that last chorus hits, and you're like, 'Ahhh!'"
Last year, Shelton revisited "Austin" as an acoustic, Amazon Original version for the 20th anniversary of his debut album Blake Shelton, which also featured hits such as "Ol' Red," "Every Time I Look at You" and "She Doesn't Know She's Got It."
Trae Patton/NBC/NBCU/Getty Blake Shelton and Kelly Clarkson
"Man – 20 years may have passed, but sometimes I still feel like the kid from Oklahoma I was back then!" he told PEOPLE at the time. "The kid who came to Nashville just wanting to sing country music."
Shelton continued, "I couldn't be prouder to celebrate the anniversary of my debut album. 'Austin' is the first song we ever released from the album, and it is still a cornerstone of my live shows."
"I'm not sure how many people actually have an 'answering machine' anymore, but the song is still as powerful and special as the first time I ever sang it," he added. "I'm grateful for all the fans who continue to connect with it like I do."
He also spoke to PEOPLE in April 2021 when the song itself — which became his first No. 1 hit on the Billboard Hot Country Songs chart — turned 20 years old.
"I would have told that kid, 'Hey man, the mullet's not as cool as you think it is,'" he told PEOPLE then. "And I would have told myself to get more rest back then. When I started I was 24 and lived life to the max back then. It's probably why I ran out of battery so soon."
"Here I am sitting here talking to you 20 years later after 'Austin' came out — not only talking to you but talking about new music that's still coming out," he added at the time. "I don't know how this happened to me, but I thank God every day. I've just been super blessed and super lucky. It's unbelievable."