Flashback: The Bee Gees Sing Medley With Glen Campbell, Willie Nelson

In this clip from 1979, the pop and country legends harmonize on "Bye Bye Love," "I Can't Stop Loving You" and more

In 1979, the Bee Gees were busy extricating themselves from the growing backlash against the decade's biggest phenomenon – disco. Arguably the biggest recording act on the planet, the brothers Gibb (Barry, Maurice and Robin) attempted to move past the dance-floor phenomenon of Saturday Night Fever, for which they penned several massive hits, including "Staying Alive" and "Night Fever," with Spirits Having Flown, a still-danceworthy LP that featured blockbusters such as "Tragedy" and "Too Much Heaven." The trio's subsequent world tour would be filmed for a TV special which captured the group on stage in July during the second of a three-night stand in Oakland, Cailfornia.

The Bee Gees Special aired November 15th, 1979, on NBC and included the siblings being interviewed by British presenter David Frost, as well as behind-the-scenes footage of tour preparation, vintage TV clips from their native Australia (where they began performing as youngsters), plus an appearance from younger brother Andy Gibb, who was breaking through on the pop charts with his own string of career-defining hits at the time.

Among the most unexpected highlights of the 90-minute special was an impromptu jam session with two of the biggest country stars of the decade, both of whom would enjoy pop crossover success: Willie Nelson and Glen Campbell. During their onstage jam, with Nelson's familiar backdrop, the Texas Lone Star flag, draped behind them, the Bee Gees, Campbell and Nelson performed a medley of rock, pop and country tunes that included the Everly Brothers' "Bye Bye Love" and "All I Have to Do Is Dream," featuring Barry Gibb and Campbell's high harmonies. After a line from the Fifties' rockabilly hit "Party Doll," Gibb once again took the lead on a soulful rendition of the Don Gibson (and Ray Charles) classic, "I Can't Stop Loving You," as Campbell and Nelson offered guitar accompaniment. Sure, the horn arrangement can't help but date the performance but it's nonetheless a great treat to hear some of the music that surely influenced the brothers early on, leading, of course, to Gibb's penning of the massive Kenny Rogers-Dolly Parton crossover hit, "Islands in the Stream" just a few years after this collaboration.

The medley concludes with the once-in-a-lifetime group performing the Bee Gees' own "To Love Somebody," (covered recently by Dwight Yoakam), as the clip transitions back to footage of the Spirits Having Flown World Tour. That song was performed yet again in 2012, when Barry Gibb, the last surviving of his brothers, made his Grand Ole Opry debut as a guest of Opry member Ricky Skaggs.