Ellona Santiago, 17, kicked off the live show for the Girls with "Till the World Ends" by Britney Spears, which prompted a standing ovation from mentor Demi Lovato.
Bespectacled bookworm Danie Geimer, 15, sang "Wrecking Ball" by Miley Cyrus, a performance that had judge Simon Cowell asking, "How do we make you not boring?"
The inspiring 13-year-old Rion Paige, who was born with arthrogryposis multiplex congenita, a rare disorder that caused a curving of the joints in her wrists, sang an emotional rendition of her mentor's hit "Skyscraper," and Khaya Cohen ended the Girls' performances with "Mercy," which prompted Cowell to say that she had "the most commercial voice" out of the four girls.
In the end it was Geimer who was sent home.
Next up were Paulina Rubio's Boys. Carlos Guevara, 16, who has Tourette's syndrome, earned stellar reviews singing "Don't You Worry Child" by Swedish House Mafia, while 24-year-old Tim Olstad's performance of "Always" earned mixed reviews.
Josh Levi, 15, tried to channel Michael Jackson, but his performance of Rihanna's "Only Girl (in the World)" only earned a "six out of 10" from Cowell, and Rubio decided to eliminate him.
One of the surprises of the night was Carlito Olivero. The 24-year-old barista sang "Maria Maria" by Carlos Santana in an energetic performance that had Cowell saying, "I run a record label. Out of everyone I've seen so far, you'd be the one I'd sign."
Grandmother Lillie McCloud, 54, got things started for Kelly Rowland's Over 25s, belting out "When A Man Loves A Woman," which Cowell described as "a bit Broadway" and "dated," while Rowland call her "the best vocalist here."
Nashville bartender, Rachel Potter, 29, sang "I Hope You Dance," which had Cowell admitting, "Astonishingly, I think you were better than [early favorite] Lillie."
Rocker Jeff Gutt, 37, performed "Try" by Pink, while James Kenney, 36, took on Daniel Merriweather's "Red." Cowell preferred Gutt's performance, calling it "bloody brilliant." Rowland must have agreed with him because she sent Kenney home.
When it came to the Groups, Roxxy Montana, a trio of sisters, sang "Royals" by Lorde, while girl group Sweet Suspense took on "I Love It" by Icona Pop.
Boyfriend-girlfriend duo Alex & Sierra again sparked fireworks singing "Blurred Lines," which led to a TMI comment from mentor Cowell, who said, "You have an amazing sexual chemistry … and I have that in my life as well."
And the country boy band, Restless Road put a twang into "Roar" by Katy Perry, which made Rowland purr in approval.
"I am totally buying every Restless Road record," she said. "I'm gonna be the one in the front row going, 'Pick me! Pick me!'"
At the end of the night, Cowell finalized the top 12 by pausing dramatically before eliminating Roxxy Montana.