The judges then deliberated on the 100 acts and reduced the field to 64 acts, who would advance to the final Boot Camp round.
Once the 64 acts were determined, each act got to select one song from a list of 35 choices, learn the song and perform it as a soloist for Cowell, Abdul, Reid, and Scherzinger.
After hearing from all 64 acts, the judges deliberated and decided who would be the show's Top 32 acts -- eight of which would each be placed in the "Boys under 30," "Girls under 30," "Over 30," and "Groups" categories.
However after revealing the competition's eight acts for the "Boys under 30," "Girls under 30" and "Over 30" categories, the judges only selected six group acts and decided to form two additional groups comprised of 14 contestants who had failed to make the cut as soloists in the boys and girls categories.
"We often look for artists that may have the potential to be solo performers, but we often cast them in groups," Reid told the 14 contestants.
"So, in other words, if... you had come in as a group, I think you would have blown away the competition. I think if you'd come in together, it would have been an absolute no-brainer, but you didn't come in as groups. But now, you are in the groups category," Cowell announced.
Once the 32 acts were determined, The X Factor's producers decided which judge would mentor each of the four categories of contestants and phoned each judge with the news.
"Really?! The Over 30s?! Alright. Alright, I can do that. It's not the girls. You didn't say girls did you?" Scherzinger told a producer once she had learned the news of her category placement.
"The Boys! I think I just won. What did Simon get? That's all I want to know," Reid joked sinisterly upon receiving his category.
"Oh my gosh, the Groups! Wow. I'm excited and I'm feeling a little bit overwhelmed already," Abdul told a producer.
"Just tell me who I've got, please... Thank you. You just made eight girls very, very happy. I'm actually more happy for them than I am for me, because I know that they want me as their mentor," Cowell said.
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Now that each judge has been assigned one category of hopefuls, next Wednesday's The X Factor broadcast will begin with the four groups of contestants each visiting their own mentor's home. Each judge will then determine which four of their eight acts will advance to the live shows.