Zach Bryan's 2024 Quittin' Time Tour kicked off on a high note on Tuesday (March 5), and he had a special surprise on deck for opening night in Chicago.

During that performance — the first of three sold-out nights in the city for Bryan — Kacey Musgraves walked out onstage to join him for a performance of "I Remember Everything," their Grammy-winning duet that debuted at the top of the Billboard Hot 100 chart in September of 2023. Bryan has performed the song solo a couple of times, but it was the first time the two recording artists have given a live rendition of their song.

Dressed in a flowing, peasant dress-inspired black-and-white ensemble, Musgraves made her way around the stage as she sang her verse, fans cheering and screaming along. Meanwhile, Bryan accompanied her on acoustic guitar, pausing briefly to introduce her to the crowd.

Related: Here Are the Lyrics to Zach Bryan + Kacey Musgraves' "I Remember Everything"

The two singers then came together for the final chorus, layering vocal harmonies over their ballad and sharing a hug before Musgraves left the stage.

Bryan and Musgraves co-wrote "I Remember Everything," and in a new interview on the TODAY Sunday Sitdown With Willie Geist, she revealed that a case of strep throat almost kept her from recording the song.

"I got asked if I wanted to do the song, and of course I was like, 'I'm down,' but I wasn't feeling well. My throat was hurting. I had just gone on this trip. And they were like, 'Well, we kind of have a deadline. If you wanna be on the song, you gotta get it in by this day. It was in, like, a couple days," she recounts.

"So I go to the studio, and I'm like, 'Man, my voice is not cooperating.' I was like, 'I hope this doesn't really suck,'" Musgraves continues. Ultimately, she managed to cut a recording she felt good about — but right after leaving the studio, she went to the doctor, where she tested positive for strep throat.

"I Remember Everything" comes off of the track list of Bryan's self-titled 2023 album. Musgraves has a new project of her own coming up: Her Deeper Well album is due out on March 15.

See the Most Played Country Song from the Year You Were Born

Who had the most played country song during the year you were born? This list is a fascinating time capsule of prevalent trends from every decade in American history. Scroll through to find your birth year and then click to listen. Some of these songs have been lost through the years, many of them for good reason!

Gallery Credit: Billy Dukes