Jason Aldean just celebrated his 21st No. 1 single "Drowns the Whiskey," a traditional country-leaning duet off his latest album Rearview Town featuring Miranda Lambert. But, as the country star revealed in Nashville during the official celebration of the song, the collaboration almost sounded a lot different.

"We weren't even thinking of ['Drown the Whiskey'] as the duet," Aldean reveals. Actually, he originally sent Lambert an entirely different song for a potential collaboration.

Aldean and the band recorded the song he first thought about bringing Lambert in on. He sent it to her for feedback. She wasn't feeling it.

"Miranda was like, 'Eh, I just don't love that song,'" Aldean recalls. After giving it more thought and listening a little longer, he agreed.

"I was like, 'Alright, let's get rid of that one,'" the star says with a slight chuckle. He went back and listened through more of the record and it just clicked. "I got to thinking and was like, this is actually the duet." Lambert agreed and added her signature touch to "Drowns the Whiskey."

Jason and Miranda's Performance at the 2018 CMAs Was a Show-Stopper

The decision to have Lambert harmonize with Aldean for almost the entire song was deliberate, too.

"I always thought we sounded great together and I wanted to do something with her voice, to make her more of a featured part," Aldean shares. The pair first sang together all the way back in 2007 on Aldean's second album Relentless. Lambert offers harmonies on the song "Grown Woman," though she wasn't credit on the song title.

So what happened to the first tune Aldean sent to Lambert? "It never made the record," he says. "At the end of the day, I wasn't loving the other one either and that's why it didn't make the record. But I think that comes when you try to force a duet. Like, 'I wanna do a song with her so let's go find a song.' But when you have a song somebody could sound great on, that's when it works, and I think that's what happened.'"

When it did happen, the team kept it pretty close to the vest, too. Even songwriters Josh Thompson, Jeff Middleton and Brandon Kinney didn't know Lambert was going to be part of the song.

Aldean has long praised Lambert as one of his favorite artists. She's one of his favorite female artists, along with current artists like Ashley McBryde, Kacey Musgraves and Maren Morris.

"I love her voice and I love what she's doing," Aldean says of Morris. "Country is her home, but she can branch out. I dig that and I think that's cool. I know a lot of people feel differently about that. But I think country music needs her. As long as this kind of stays her home, I think that's great."

It's a debate Aldean knows a lot about, considering how many feathers he ruffled in the mid-2000s when he brought a harder rock edge to his sound. Twenty-one chart-topping singles into his career, he still doesn't take the success for granted.

"To me, the number doesn't matter so much as feeling like 13 years into this deal, people still like what I'm doing," he says. "That's the thing that's cool."

See Pics of Jason and Brittany Aldean's Fairytale Mansion — It's for Sale: