X Factor Six Chair Challenge: Everything you need to know about the brutal journey to Judges' Houses

What is Six Chair Challenge?

Introduced in 2013, this is the process in which the final six acts in each category are selected.

Falling between Bootcamp and Judges' Houses, it sees the successful singers who got a yes at Bootcamp vie for a place at Judges' Houses by performing for Simon Cowell, Sharon Osbourne, Nicole Scherzinger and Louis Walsh in front of a live arena audience.

The six acts eventually seemed to be the best in each category then go through to the final stage before the live shows.

How does Six Chair Challenge work?

It's basically exactly what happens in a gladiator's arena. After each singer's performance, they are told by the relevant judge for their category whether they have 'won' one of the six seats available. If they have, they sit down. If they haven't, they're immediately sent home.

But the drama is only just beginning once all six chairs are filled. None of the acts are actually safe until every single singer has performed, because even if someone is handed a chair, they can be usurped at any time by another person.

If someone comes out and delivers a performance that the judge deems more worthy, one of the six seated acts will be booted off the show and replaced with another singer.

There can be a cappella sing-offs, plenty of booing from the arena audience and judges left in despair as their decisions are derided by the baying crowd.

In this dystopian game of musical chairs, there's always tears aplenty.

Why is Six Chair Challenge so controversial?

Basically, because of moments like this:

The live audience who sit in for the Six Chair Challenge at Wembley Arena get thoroughly involved with the decisions, chanting "off, off" at singers they don't deem good enough, and screaming the number of the singer's seat they want to see usurped.

With performers' hopes and dreams being made and then instantly dashed it's something of a psychological rollercoaster - particularly when the added element of the live audience is thrown into the mix. Because even when they think they're safe, they rarely are. There are a cappella sing-offs as contestants are told to stand up and re-audition for their spot, and the deliberations can go on well into the night in the arena.

"The Six Chair Challenge was hell for me," admitted former judge Cheryl in 2014. "I didn’t enjoy it one little bit."

Reports swirling from the show this year have suggested that both Nicole Scherzinger and Sharon Osbourne were left in tears after having to narrow down their singers ahead of Judges' Houses, with Nicole even having to temporarily leave the set after the emotion got too much for her. Other rumours have even hinted that one group was even split up during the Six Chair Challenge.

This is all on top of the fact that this year, a change in the format will now see one judge having to sit away from all of the others whilst they make their decisions.

The X Factor: Six Chair Challenge airs at 7.30pm on Sunday October 8