Adam who?! While it's true that Maroon 5 frontman Levine and Blake Shelton have gotten close over their long tenure working together as judges on The Voice, and that their quirky, oft-antagonistic friendship has been well-documented, Levine is far from Shelton's first bromantic love interest. That title belongs to Trace Adkins -- and we've got the pics to prove it.

Many fans may know that the dynamic duo's forthcoming duet, "Hell Right" (out Aug. 16), isn't the first time Shelton and Adkins have collaborated on a song. Back in 2009, they teamed up for "Hillbilly Bone," a platinum-certified hit that went No. 1 at country radio and notched an ACM Award for Vocal Event of the Year.

While discussing "Hell Right" in advance of its release, Shelton sang the praises of his duet parter. "He's got that low, deep, big voice, and he's so great at he ad-lib stuff, and he just brings a certain quality to any recording that nobody else can touch," he says of Adkins. "I mean, the guy's got so much personalty in his voice and the way he sings, and i still think that he's one of the most underrated country artists out there."

But wait, there's more: The two have toured and performed together, and Shelton even brought Adkins onto the set of The Voice as his Battle Rounds advisor in 2018. They've been known to share an onstage bear hug or two, and even the occasional kiss on the cheek. Flip through the gallery below to see photos of all the friendly PDA, and other snapshots of Shelton and Adkins' friendship through the years.

For a country star, there's no accolade higher than becoming a member of the Grand Ole Opry. In 2010, it was Adkins who invited Shelton to join the hallowed hall. If that's not love, we don't know what is.

 Blake Shelton and Trace Adkins' Bromance Through the Years