Willie Nelson, Kris Kristofferson and Merle Haggard to Release Album

Country's Finest

Willie Nelson and Kris Kristofferson kicked off the performance with "Highwayman," with Blake Shelton joining Merle Haggard for his hit "Okie from Muskogee." The four musicians then joined for "Mammas, Don't Let Your Babies Grow Up to Be Cowboys," which Nelson recorded with Waylon Jennings in 1978.

This article first appeared on Billboard.com.

Willie Nelson, Kris Kristofferson and Merle Haggard brought the house down with Blake Shelton at the Grammy Awards on Sunday night, and it's looking like the trio of country music legends will carry that momentum back to the recording studio.

PHOTOS: Grammys 2014: Best and Worst Moments

Before they performed "Highwayman," "Okie From Muskogee" and "Mammas, Don't Let Your Babies Grow Up to Be Cowboys" -- the latter inspired the likes of Jay Z, Beyonce and Yoko Ono to stand and sway -- the icons told Billboard a collaborative album is in the works.

"We're working on one now, yeah," says Nelson, adding that they'll release it "as soon as we get it together."

While they do have shared histories, the three have never collaborated on the same record, as far as we can tell. Nelson is the common thread, having worked with Kristofferson in The Highwaymen and with Haggard on 1983's chart-topping "Pancho and Lefty." There have been plenty of other projects over the years, but it doesn't appear Kristofferson and Haggard have ever joined forces.

STORY: 15 Things Seen and Heard at the 2014 Grammy Awards

Meanwhile, asked about a new law in Colorado allowing the sale of recreational marijuana, the trio's resident pot booster said there's a whiff of inevitability in the air. "It's just a matter of time till the whole country will wake up and realize that this is where we're going and get ready for it," Nelson said.