On Saturday, 16 acts will go head-to-head in the live shows. Viewers have already been introduced to 12 acts, but this weekend we will also find out who the chosen four wildcards are.
To choose the wildcards, each judge has picked a returning act for another judge, and Simon had the responsibility of picking Mel's.
Although it's supposed to be kept top secret, it seems Scary Spice couldn't quite help herself, as she let slip during an interview on Good Morning Britain that her wildcard act is from her hometown of Leeds!
Mel said: "I'm so happy with mine. Simon chose mine. I can't tell you who it is, but he's from my hometown!"
Mel quickly burst out laughing with interviewer Richard Arnold, and her X Factor finalists Andrea Faustini, Paul Akister and Jake Quickenden began to laugh once they realised what she had said.
Richard later said: "Spoiler alert! It doesn't take a rocket scientist to work that one out!"
Of course, viewers will remember that Mel was fond of guitar-playing singer Jack from his first room audition.
Jack told the judges he was from Leeds, in West Yorkshire, before explaining to Mel that he lived in Castleford.
Mel took Jack through to the Judges' Houses stage of the competition, but he didn't make her final three, as she chose to take Andrea, Paul and Jake through to the live shows.
Delivering the bad news, Mel told Jack at the time: "This is so hard because I know what's going to be expected of the people I put through. This is the toughest decision I've had to make."
But with each judge being given the responsibility of a choosing a wildcard act, has Simon's decision meant Jack will be joining the boys for the live shows?!
Earlier this week, it was also rumoured that boyband Overload had been chosen to join Louis' groups, while 20-year-old Lola Saunders was rumoured to be joining Cheryl Fernandez-Versini's girls' category.
Watch Jake's performance of Beyoncé's 'Halo' below: