The American Idol alum performed Andrea Bocelli and Céline Dion's iconic song alongside contestant Willie Spence

Talk about vocals!

On Sunday's episode of American Idol, Katharine McPhee joined contestant Willie Spence for a jaw-dropping rendition of "The Prayer" by Andrea Bocelli and Céline Dion.

McPhee, 37, who recently gave birth to baby Rennie in late March and also competed on the singing show in 2006, proved to be the perfect duet to the contestant judge Lionel Richie called "Willie Pavarotti."

"You do no wrong in my eyes," Luke Bryan said after the performance. "Part of being a star is making people fall in love with you and, man, I am in love with you. And I am in love with the way you go about being on stage, and the way you go about singing and the place it comes from. It's amazing."

Credit: Eric McCandless/ABC

"In our business, you don't want to be a singer, you want to be a stylist," added Richie, 71. "You have your own lane, and it's just mesmerizing to watch you."

Backstage, McPhee praised Spence for his ability to make an Andrea Bocelli song "something that Willie would sing." Meanwhile, Katy Perry called their rendition "goosebumps central everywhere."

"To win this, it's about song choice," Perry, 36, said. "And it's about those amazing classic songs that other powerhouses sing that shows that you are also a powerhouse."

Credit: Eric McCandless/ABC

Before his duet with McPhee, Spence hit the stage for a rendition of "Wind Beneath My Wings" by Bette Midler, a performance he dedicated to his late grandfather. On Monday night, the other 12 singers in the top 24 will perform two songs before eight are eliminated following the two-night All-Star duets.

American Idol airs Sundays and Mondays at 8 p.m. ET on ABC.