Shortly after 8 p.m. on Saturday, just before his appearance as the musical guest on NBC’s “Saturday Night Live,” country star Chris Stapleton posted a video to his social media accounts that sparked a bit of a frenzy.

“Tonight we’ve got some extra Kentucky in NYC,” the caption read, as the clip showed Stapleton in front of the camera. Suddenly, a mischievous-looking Sturgill Simpson — fellow country singer and Kentucky native — appeared behind him to grab his cowboy hat. That was enough to get fans riled up on social media, as the next four hours became a guessing game of what was about to happen.

When Stapleton’s first performance started, he stood in the lone spotlight as he strummed the opening notes of “Midnight Train to Memphis.” Then the lights kicked on and to his left was Simpson, playing guitar. But he wasn’t only part of the band — he belted out the second verse, as well. He also joined Stapleton for his next song, “Hard Livin’,” with a guitar solo.

The camera frequently panned to Simpson, though his name wasn’t announced on-air until the second performance, when host Will Ferrell introduced him and Stapleton. Throughout the show, the ecstatic tweets poured in.

So, why was Simpson’s surprise cameo such a big deal? First, they’re both hugely popular singers with a crossover fan base, many of whom were thrilled to see this rare collaboration. Stapleton’s 2015 solo debut, “Traveller,” has been the top-selling country album for the last two years; the second-highest-selling country album of 2017 was his sophomore record, “From A Room: Volume 1.” Simpson has also earned rabidly loyal fans through years of touring and was nominated for album of the year at the 2017 Grammys for his acclaimed “A Sailor’s Guide to Earth.” (He lost to Adele but won best country album.)

Perhaps more importantly, for many fans, seeing Simpson alongside Stapleton in front of millions of viewers was a vindication for traditional country music — the two of them, along with Jason Isbell, are often mentioned in the same breath as country music “saviors,” who stay away from the pop-centric production and party song culture frequently found in Nashville.

“If you feel like real country music died with the 1970s and gave way to a genre that’s the musical equivalent of Walmart — monolithic, cheap, and eroding the soul of small-town America . . . there’s a new gang of outlaws on the make,” GQ recently trumpeted of the three Dave Cobb-produced singers, with the headline, “Meet Three Country Badasses Who Are Shaking Up the Nashville Establishment.”

While Stapleton has broken through to the mainstream in the last few years, becoming the rare Nashville singer-songwriter who appeals to die-hard traditionalists and listeners who love modern country music, Simpson is still considered a niche singer who isn’t played on country radio or included in award shows. He’s a vocal critic of Nashville gatekeepers who ignore singers such as him and Isbell.

“They are well aware that we don’t need them,” Simpson wrote in 2016. “Our last albums went to #1 without any help from the Mainstream Country Music establishment . . . and our next albums will too.” In November, while the Country Music Association Awards took place at the Bridgestone Arena in Nashville, Simpson stood outside the venue and joked about how he wasn’t allowed in — while he busked on the street with his Grammy trophy in his guitar case.

Saturday marked the second SNL stint for both Stapleton and Simpson, who have been on separately as musical guests in the past, though this Stapleton appearance was on the eve of Sunday’s Grammy Awards, where he’s nominated for country album and country solo performance. By inviting Simpson to share his spotlight, Stapleton sent a powerful reminder of what can happen when a Nashville “outsider” is given the chance to shine on a national platform — and possibly inspire others to follow suit.

(This post has been updated.)

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