When Joe Nichols recorded his album 'Real Things,' he found a song that truly touched him, and he just knew it would be a huge hit for him. Instead, that song found another home with his pal Blake Shelton. The song? 'Who Are You When I'm Not Looking.'

"'Who Are You' is one of the mistakes you make along the way; the woulda, coulda, shoulda that has happened, and you just wished things would've been different," Joe tells The Boot. "When we cut [it], I begged everybody who would listen, I begged for that to be a single, for that to be the first single. But a lot of people who get paid a lot more than I do make a lot of the calls, and it didn't go my way. That song was brilliantly written, and the production Brent Rowan did on it was immaculate. He just did a fantastic job, and I was really proud of my part. I really thought that it could have been a really special song for us."

Even though Joe felt a bit of disappointment that the song was not a single for him, he's thrilled that it is for his longtime friend. "The one thing I am proud of now is that it's found a home with Blake, and Blake's having some significant success with it," he says. "It's the hit it should've been, and I'm glad he's the guy that cut it and that he's going to have the hit on it. I'm happy for the writers, and I'm happy for Blake. We screwed it up, and hopefully they don't [laughs]."

Blake fell in love with the song at first listen, and was both shocked and excited it was not released as a single for Joe. "I'm a huge Joe Nichols fan. If he puts out a record, I'm one of the first people pushing old ladies over at Walmart to get one. I'll punch 'em if I have to," Blake tells The Boot with a laugh. "I love Joe, and I've known him for years. It's beyond just a friendship. I'm a fan of his voice and just what he does. He's got this thing about him that takes me back to why I wanted to do this to begin with [and why I moved to Nashville]."

"All that aside, he had put out an album called 'Real Things,'" Blake continues. "I went and bought the record and I was listening to it, and 'Who Are You When I'm Not Looking' came on, and I remember actually being excited for Joe when I heard the song. I was going, 'Oh my gosh, this will be his signature song. This will be the biggest song he's ever made.' After the record came and went, and they came out with, I guess 'Gimmie That Girl' or whatever his first single was off his next record -- hell, man! They screwed up. I'm putting that sucker out! I just honestly tried to do as good a job as Joe did on it. Thank you to Joe for getting me that song. [laughs]"

Watch Blake perform 'Who Are You When I'm Not Looking' live in our studio below.

Joe is currently scaling the country charts with his latest hit, 'The Shape I'm In,' which appears on his new 'Greatest Hits' collection, in stores now.

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