In 1971, Loretta Lynn and Conway Twitty released one of their most famous duets, "After the Fire Is Gone." The song became their first No. 1 single together, and Lynn and Twitty endure as one of country music's most iconic singing duos -- just ask Garth Brooks and Trisha Yearwood.

As part of an upcoming documentary about Lynn's life and career, Brooks and Yearwood sat down to discuss Lynn and Twitty's musical partnership.

"When these two voices hit, it creates this dimension that you can't get singular, one without the other," Brooks explains, with Yearwood adding, "And that's why I've always enjoyed singing with Garth ... There's this energy there that's created together."

Press play on the video above to hear more of Brooks and Yearwood's thoughts on what made Lynn and Twitty a perfect professional pair -- and stick with it 'til the end, because hearing the country couple put their own spin on "After the Fire Is Gone" will give you goosebumps!

Loretta Lynn: Still a Mountain Girl is set to debut on PBS on March 4. The show will explore Lynn’s road to stardom as she went from a rural Kentucky farm girl to a world-class superstar; it will also show the singer trying to maintain balance in her home life and career.

“I think I’ve done quite a bit,” Lynn reflects. “I’m probably one of the girl singers who have helped other girl singers get in the business, because it is harder for girls to get on labels and be out there.”

Also on March 4, Lynn's new album, Full Circle, is set for release.

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