Carrie Underwood makes a vocal appearance on legendary crooner Tony Bennett's 'Duets II' album. In this behind-the-scenes clip of the duet from Bennett's recent PBS special, you can see how Underwood's personality blends as well with Bennett's as their smooth voices do on the the standard hit. Underwood says singing with the icon was a no-brainer for her.

“I would have sang anything with Tony," she says. "Whatever he wanted, I was there. He requested ‘It Had To Be You’ to sing with me." See the video clip to watch a version of the two stars singing the duet together -- it's obvious how much Underwood respects the older talent.

"Being able to be standing there with Tony on a stage and seeing the band members and the lights and it’s dark, it was a very organic way of doing things," she says. "And I’ve never been lucky enough to get to do something like that before. He wants to do duets with people as themselves and have them bring their thing and him bring his thing, and I respect that so much … There’s just so much more emotion that can come out when you’re in the moment like that.”

For this project, Bennett will also be releasing duets with the likes of Andrea Boccelli, Lady Gaga, Amy Winehouse, Michael Buble and others.

Watch Carrie Underwood Performing 'It Had to Be You' With Tony Bennett