'American Idol': Katy Perry calls Laci Kaye Booth her 'favorite' after emotional duet

"American Idol" front-runners have emerged as the competition continues its Top 20 round. 

During Sunday's first episode of celebrity duets, the sprightly Uche electrified as he danced and belted his way through Shaggy's "I Need Your Love" alongside the Jamaican singer. And Madison VanDenburg pulled off no easy feat, matching Pat Benatar's powerful vocals as they performed "We Belong" with guitarist Neil Giraldo. 

But once again, it was Texas native Laci Kaye Booth who stole the show, after flooring the judges just last week with her country spin on Cheap Trick's "I Want You to Want Me." 

Paired with country star Brett Young, the two sang a sizzling rendition of his breakup ballad "Mercy," all while sitting on stools center stage and accompanied by just a piano. 

"Laci has this very smoky, interesting voice that almost looks like it doesn't come out of her, but once it does, it also seems so natural," Young said of his singing partner in a pretaped interview. 

The judges were similarly complimentary of Booth's emotional performance. 

"It was so believable," Lionel Richie said after. "I actually thought I was watching a serious love affair on that stage because it was delivered so well."

"From the moment you walk onstage, you sprinkle stardust everywhere," Katy Perry said. "I thought I was watching something on the Grammys, like 'best new artist,' I don't know."

"I don't want to play favorites," she added, shrugging and grinning. "But fill in the blank." 

When judge Luke Bryan joked that Perry was won over by a country artist, Perry responded, "It's not about genre, it's about feeling." 

The episode ended with the elimination of three contestants: Bumbly, Shawn Robinson and Kate Barnette. "Idol" duets continue during Monday's episode (ABC, 8 EDT/PDT), which will reveal the full Top 14.