Steven Tyler jumped at the chance to duet with Carrie Underwood on her song Undo It last year, because he fell in love with the track when he thought it had been written for his band Aerosmith.

The rock frontman first stumbled across the tune in 2009 while visiting a songwriter pal of his, and he assumed it was being submitted to Aerosmith to try out.

He was left disappointed when he learned the track had already been recorded by Underwood, but Tyler finally got the opportunity to belt it out when he was invited to perform the song with the singing beauty at the Academy of Country Music Awards in 2011.

He tells the Associated Press, "I just love to sing and I love her stuff. A good friend of mine writes songs with her. When I heard 'Undo It,' I said, 'What is that? That is an Aerosmith song, right? I am going to finish recording that with you?' He said, 'No, I wrote that with Carrie, it is coming out in a week.'"

And the current American Idol judge admits he fell for the talent show's former winner the minute she opened her mouth in rehearsals: "I met her and it was all over after that, once I looked into her eyes. She opened her mouth and sang and she is that good. I loved singing with her."

Tyler has been a big fan of Underwood's ever since, and they are set to reunite on Saturday (04Feb12) when they perform together again for Country Music Television's Crossroads special in Indianapolis, Indiana. (MT/WNWA/KL)