This week, Blake Shelton tops the country singles chart with his latest hit, 'Who Are You When I'm Not Looking,' scoring the singer his eighth overall No. 1 hit.

The song was originally recorded by Joe Nichols back in 2005 on his 'III' album. Luckily for Shelton, the song was never released as a single although it was supposed to be at some point, according to John Wiggins, who penned the tune back in 2003 with Earl Bud Lee.

"It was slated to be a single on Joe -- you know how they put the little song titles on a sticker on the front of the CD case [saying what] singles or featured songs are on the CD," Wiggins tells Taste of Country. "The record company told me it was going to be a single, and for whatever reason it wasn't a single. They pulled the whole project after the second single, and I thought that was it."

The song had its second chance when Shelton cut the tune for his 'All About Tonight' album and released it as the follow-up single to the title track, which also topped the country singles chart.

"I heard Blake say in an interview that he heard the song on Joe's CD, and he said he thought it was going to be a career record for Joe," Wiggins says. "When he found out it wasn't going to be a single, he said, 'I knew it would be a career record for me.'"