The 24-year-old single mother from Toledo, Ohio, performed Creedence Clearwater Revival's "Long As I Can See The Light" to rave reviews from the judges Wednesday, the day after she was hospitalized for an undisclosed malady that prompted the show's producers to switch the semifinal performance order at the last minute.
"I feel good," she told Ryan Seacrest, the Fox singing competition's host. "I'm a tough cookie."
Randy Jackson called Bowersox's soulful rendition "the truth," while Ellen DeGeneres said the dreadlocked singer had "pure, raw, natural talent." Kara DioGuardi informed Bowersox that she "hit a new level tonight."
Simon Cowell admitted he "completely underestimated" Bowersox after her performance last week of Alanis Morissette's "Hand In My Pocket."
"I think we've got a serious artist with you," Cowell said.
Photos: "Idol" Worship
Lilly Scott, the 20-year-old musician from Denver, satisfied the panel with her rendition of Sam Cooke's "It's Been a Long Time Coming." And the often divided judges were equally impressed with the range displayed by Siobhan Magnus, the 20-year-old glass blower from Marstons Mills, Mass., during her performance of Aretha Franklin's "Think."
"You are so bold and so fearless," exclaimed Jackson.
Other singers weren't as favored.
Didi Benami, the 23-year-old waitress from Los Angeles, was almost brought to tears after the judges slammed her uninspired interpretation of Bill Withers' "Lean On Me." But Haeley Vaughn, the 16-year-old high school student from Fort Collins, Colo., kept smiling as they ripped down her version of Miley Cyrus' "The Climb."
"You need about a year of strengthening your instrument," DioGuardi advised Vaughn.
Among the singers who turned in so-so performances: 24-year-old event coordinator Lacey Brown of Amarillo, Texas, with Sixpence None The Richer's "Kiss Me," 19-year-old college student Katelyn Epperly of West Des Moines, Iowa, with Coldplay's "The Scientist," and 24-year-old preschool teacher Paige Miles of Houston, Texas, with Kelly Clarkson's "Walk Away."
The two male and two female semifinalists with the fewest viewer votes are slated to be sent home Thursday, leaving 16 contestants to vie for a spot as one of the top 12 finalists next week. Thursday's episode will also feature bespectacled season-eight finalist Danny Gokey performing his single, "My Best Days Are Ahead of Me."