IT WAS an X Factor roller coaster ride for Rockhampton singer Zach Russell last night.

The 22-year-old made it through to the Top 24 but was devastated when his older brother Aaron missed out on the Channel 7 talent show.

"It's not fair that you don't get a chance," Zach said through tears.

In the final round of super boot camp, the Top 24 contestants were selected for the groups, under-25 girls, under-25 boys and over-25s categories based on their solo performances.

And just as it looked like Zach had also missed out on the under-25 boys category, he was called back in to be a part of the boy super group.

The Top 24 advance to the home visits round next week, when they will travel overseas to be mentored by Ke$ha, Alicia Keys, Usher and One Direction.

The members for a boy band and a girl band were hand picked by the four celebrity coaches.

The two super groups are joined in the groups category by four already existing groups which tried out for the show: four-piece Fortunate, female duo Good Question, Australia's self-proclaimed answer to One Direction What About Tonight and male duo D&D.