But who recaptured the '80s era of legwarmers, headbands and big hair the best (not counting Keith Urban, who opened the show sporting a clip-on mullet that had Ryan Seacrest calling him "Billy Ray Urban")?
Here are the singers who had "The Eye of the Tiger" and those who were more "Borderline."
The Eye of the TigerRocker Caleb Johnson finally softened it up, singing a powerfully reverential version of "Faithfully" filled with fireworks (and Urban holding up his iPhone "lighter" in admiration).
"I have been waiting for that subtlety. You did it," said Harry Connick Jr., while Jennifer Lopez called it "amazing," saying it's "no small task to take on Steve Perry."
Although the judges weren't unanimous in their praise of Alex Preston and Jena Irene's reimagined '80s tunes, their unique takes were still standouts.
Preston's guitar-string-heavy reinvention of "Every Breath You Take" into a sweet love song had Lopez missing the "soul of the song," but Urban and Connick raving.
"You grab my attention like that," Urban said, snapping his finger, adding his version was a "bold dismantling."
Irene reinvented Joan Jett's "I Love Rock 'n' Roll," starting the rock song slowly on a piano before turning it into a bluesy number.
"I love the originality you always bring," said Urban, a take with which Connick agreed. "You're trying and twisting and manipulating these arrangements."
However, Connick and Lopez, who said the arrangement "languished" in the middle, told her to ignore the advice of Idol producers and do her own thing on stage.
BorderlineAfter last week's dramatic save, the judges felt Sam Woolf's stripped down version of "Time After Time" was vocally strong but again lacked connection.
"Look up young Ricky Nelson on YouTube," instructed Connick. "Watch what he does."
Connick said Dexter Roberts earned himself a free week to "rock out" after last week's performance, and the country crooner's version of "Keep Your Hands to Yourself" needed something "completely unexpected," according to Urban.
Malaya Watson took on "Through the Fire," and the judges agreed with Connick's assessment that although "not a lot of people that can hit that Chaka note in full voice … the entire performance was geared up for that moment."
Jessica Meuse sounded strong but looked uncomfortable without her guitar singing "Call Me," and Urban said her performances were akin to being "close to the door, ready to go into the party."
Lopez called C.J. Harris's version of "Free Fallin'" "shaky" and Connick gave him yet another lesson on pitch, although Urban called it a "great rendition" due to the "survivor tone to your voice."
Results air Thursday (9 p.m. ET) on Fox.