X Factor's Jennifer Phillips says Simon Cowell would have had a "problem" if he'd booted her from the Six Chair Challenge

“I was thinking, ‘Simon [Cowell], if you move me you’re gonna have a problem cause I’m not moving,” she tells RadioTimes.com. “I've worked hard. Even before the Six Chairs I had 24 hours without sleep on my song. Not just learning my words, but connecting to the song, connecting to the words, so my performance could be more effective. And it's the hard work behind what you do that pays off. So, I was just saying, ‘God, after all this, I need to stay on my chair.’ They would have needed security, paramedics and the police to come out because I was not going to move!"

There was never any doubt of her going through, of course. Phillips, 34, has a voice that could crack rock – a voice that wowed everyone in her first audition, where she sang Mary Mary's Shackles. In fact, when it came to filming the Six Chair Challenge, that episode had recently aired, making her a star to the audience. "That was really encouraging for me, it inspired me to do a better performance."

Still, nothing quite prepares you for the event itself, which Phillips describes as like being "on death row."

"Nerve-wrecking is not the word," she says. "I didn’t realise we had that many nerves in our body. I was doing all kinds of stuff: sitting down, marching around, standing up, doing all sorts of crazy stuff.

"At one point I thought, 'You know what Jen? You have to focus.' So many mental blockages. 'Oh my god, I’ve forgotten the words!' 'Oh god please don’t embarrass yourself on national TV!' But then you walk on stage, and the audience is with you and the adrenaline is just 'bam' and you go back to your memory and you think, 'I need my chair. I’ve gotta sing. I've gotta sing!'"

Phillips, who is in Simon Cowell's Overs category, is now focusing on the next stage of the competition, Judges' Houses, which she hopes will take her to Los Angeles. "Shopping!"

However, in what is already a strong Overs group, Phillips is considered one of the firm favourites. Is she confident in her ability to win the whole thing?

"I'm not sure," she says "Because [the other contestants] have not just got vocals but massive personalities. And they can dance! I'm probably the only person with two left legs! It might end up like, 'thank you very much Jennifer but you're out!'

"But then it's not over 'til it's over – even though we're in the overs!"

The X Factor continues next Saturday on ITV