A couple of classic rock icons paid tribute to a country legend on Thursday night (April 6): Warren Haynes and ZZ Top's Billy Gibbons covered Merle Haggard's hit song "Workin' Man Blues" during the Sing Me Back Home: The Music of Merle Haggard tribute concert in Nashville. Readers can press play above to watch their performance.

Originally written and recorded by Haggard for his 1969 album A Portrait of Merle Haggard, "Workin' Man Blues" would become a signature song for the iconic singer, with the full power of his guitar rounding out the song's rock 'n' roll vibes and cementing Haggard as one of the pioneers of what came to be known as the "Bakersfield sound." "Workin' Man Blues" also played to one of Haggard's largest fan bases, as it praises the hard-working values of the American blue-collar worker.

The choice to have Gibbons and Haynes cover "Workin' Man Blues" is one that made the entire crowd go crazy -- and even some of the backing musicians, too! In the clip above, it's fun to see the band behind Gibbons and Haynes look on in awe.

Along with his illustrious tenure as a longtime guitarist for the Allman Brothers Band and as founding member of the jam band Gov’t Mule, Haynes has found considerable success in the Americana world; he released a solo album, Ashes & Dust, in 2015. Gibbons has also made a strong foray into country music over the past few years, along with his status in the classic rock outfit ZZ Top: He performed with Jake Owen at the 2013 American Country Awards and shared the stage with Miranda Lambert and Keith Urban at last year's ACM Awards.

Other artists who took the stage to honor Haggard during Sing Me Back Home: The Music of Merle Haggard included Dierks Bentley, John Mellencamp, Keith Richards, Kenny Chesney, Sheryl Crow and Loretta Lynn. A portion of the proceeds from the event benefited the TJ Martell Foundation.

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