Carrie Underwood would never write a song about Tony Romo.

The country singer - whose track 'Cowboy Casanova' was rumoured to be about her American footballer ex-boyfriend, who she dated until 2007 - insists the song is about someone else as she would never be inspired by someone who hurt her.

She said: "No. I would never immortalize a guy that did me wrong. I would never give him that much credit."

The former 'American Idol' winner also took a swipe at the show's judge Simon Cowell.

She said: "Simon's obviously very smart. But he's not the smartest person I know."

Recalling her time on the show, Carried admitted she almost never made the auditions because she was so nervous.

She told America's Esquire magazine: "I was so nervous when I was on my way to LA. I'd never been on a plane, and I was going alone. I kind of got teary-eyed.

"My dad was driving, and he said, 'If you want to go home, we can go home, and you never have to think about this again. And I thought, If I don't go, I'm choosing for this not to happen. It will be my choice. "So I figured it would be easier for me to get kicked off 'American Idol' than to have it be my own decision."