John Mayer has a friend in Chris Stapleton. He has a pretty good songwriting partner, too, as the pair proved on stage in Nashville on Thursday (Aug. 8).

While Mayer didn't officially announce the name of the new song they performed, fans have started calling it "I Just Remembered That I Didn't Care" due to the refrain of the mid-tempo, Phil Collins-esque groove. Stapleton sings the chorus and second verse of an original song backed by drums, guitars, keys and bass.

All indications point to this track being one for a future Mayer project, if it ends up anywhere. Before bringing Stapleton onstage late in his set, the pop-rocker explained how they ended up working together.

"I said, 'You wanna do one of my songs or one of your songs?' And he said, 'We could do either or we could just write a song and play it,'" Mayer says in the above video. "I said, 'Challenge accepted."

"I Just Remembered That I Didn't Care" was written on Wednesday during an off day for both men. USA Today shares that Stapleton also performed Mayer's classic "Slow Dancing in a Burning Room" during the 26-song set.

December will mark two years between Stapleton albums, and there has been no chatter about new original music for him. The "Millionaire" singer has done several collaborations however, including songs with Ed Sheeran and Bruno Mars, a song with Sheryl Crow and another with Pink.

Stapleton famously got his break on the same Nashville stage at the 2015 CMA Awards when Justin Timberlake joined him for two songs, including "Tennessee Whiskey."

WATCH: The Secret History of Chris Stapleton's Breakout Night

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