The 13-year-old impressed the music mogul with her unique rendition of the Backstreet Boys hit I Want It That Way.
Despite her tender age Rachel proved she had confidence beyond her years and speaking before her performance she asserted: ‘I’m definitely ready’.
Little star: 13-year-old Rachel Crow blew Simon Cowell away with her rendition of Backstreet Boys hit song I Want It That Way
She added: ‘I want this more than anything and what every happens it is going to be epic.’
After her moving performance Simon gushed: ‘Well done you.’
And as he discussed her performance with the rest of his team he said: ‘That was unbelievable. Oh my god I like the fact she takes risks I like the deep tones.’
Big confidence: Despite her young age the teenager showed a considerable amount of confidence and said she was ready for the competiton
Unbelievable: Simon gushed to his team about Rachel's performance but worried that she might not be able to handle the competition as well as others
While Rachel clearly made a big impression on Simon he did admit he worried if she was really ready for the competition.
He said: ‘Maybe it’s just her bad luck that she is in this category with people who could probably deal with the pressure better.’
Powerful: Melanie Amaro showed off her vocal ability by belting out a huge ballad which left Simon bowled over
Impressed: After her performance Simon fell back and pretended to rip up a piece of paper as if to say the competition was over
Speaking to Steve Jones Rachel reviewed her performance and said: ‘I feel it went pretty good. I put my heart into it.’
It wasn’t just Rachel who was impressing Simon and he literally flung himself down onto the sofa after listening to Melanie Amaro.
She performed a soulful song which showcased her incredible ability and after her performance Simon fell back and pretended to rip up a piece of paper as if to say the competition was over.
Mixed reviews: Rihanna and LA Reid had mixed feelings over Brennin Hunt's performance
'I want to be bigger than Lady Gaga': Brennin Hunt has high hopes but Rihanna found him a bit 'corny'
But despite Melanie’s impressive rendition Simon and his camp did have concerns for her and wondered if she would be able to perform contemporary songs as well as big ballads.
Simon might also be worrying about how the show is going down in the U.S. and according to The Sun the X Factor USA's ratings slipped to just 10.8million on Thursday night.
Mr Cowell wasn't the only one questioning contestants abilities and Rihanna and LA Reid are confused over Brennin Hunt.
All about the art: Chris Rene impressed Rihanna and Reid with his version of Everyday People
Big confidence: Marcus Canty went down well with his version of K-Ci and JoJo's 'All My Life'
The 26-year-old brought bags of confidence to the table ahead of his performance of Corinne Bailey Rae's Like A Star.
He explained: 'I’ve tried every avenue, this is life changing, this is very important to me,' before admitting 'I want to be bigger than Lady Gaga.'
But Rihanna's verdict on the audition was mixed and she said: 'I think he is beautiful and his tone is correct at times but he is a little bit corny'.
Good job: The Stereo Hoggz impressed Pharrell Williams and Paula Abdul with their energetic performance of Heard It Through The Grape Vine
Excited: Speaking about the band Pharrell said: 'That lead kid is like an all mowtown kid mixed with Ginuwine and Paula agreed before getting up to jump on him
Second chance: The teen group Intensity entered as individuals but were put through as a group and sang Ting Tings Not My Name
Over in Santa Barbara The Stereo Hoggz impressed Pharrell Williams and Paula Abdul with their energetic performance of Heard It Through The Grape Vine.
Pharell remarked: 'That lead kid is like an all mowtown kid mixed with Ginuwine,' but he warned that, 'They have to be a constellation they can’t be just one star.'
Josh Krajcik impressed Nicole and Enrique with his version of Roberta Flack's 'The First Time I Saw Your Face' but Nicole was worried he wasn't a typical star.
Very pleased: Josh impressed the judges but Nicole was worried he wasn't a typical star
Talented: Josh Krajcik impressed Nicole and Enrique with his version of Roberta Flack's 'The First Time I Saw Your Face'