Spears decided to send home Diamond White in the first results show last night (November 1), choosing to keep Arin Ray around for another week.
However, the judge admitted to reporters backstage that she struggled with the decision.
"She has an amazing voice for such a young age," Spears told E! Online. "It was really hard to do that."
Spears also explained her decision to save Ray, saying: "I was looking for that eye of the tiger, that 'it factor', that someone who just kind of wows you and takes you in."
Meanwhile, White suggested that she believes "another awesome door" will open for her in the future.
David Correy, Willie Jones and Sister C were also last night eliminated from The X Factor USA, which continues on Wednesday on Fox.
Photo gallery - The X Factor USA results show:
Copyright: Fox Brian Dowling