Katy Perry

A source says Underwood was not producers' first choice.

Surely that's not Luke's fault ... right?

Luke Bryan discusses Katy Perry's exit from American Idol, highlighting their ongoing and growing friendship.

Did you know these celebrity couples once tied the knot? Too bad they didn't last. (Well, except for a few of them...)

After viewers criticized Katy Perry's comments, the contestant offered her perspective on social media.

He's the resident country expert on 'American Idol.'

They served up a soaring rendition of their pop-leaning duet.

Rhett and Perry come together in this music video for an abstract, cinematic visual interpretation of their duet.

Host Ryan Seacrest will also return for Season 21.

She says she may get back to her singer-songwriter roots.

It's the first time the song has been performed live.

It was one of the hands-down highlights of the night.