Just 45 acts remain from the thousands who applied and the hundreds who auditioned, and they will battle it out for the prize of £250,000 and a spot at the Royal Variety Performance.
Teenage boys Bars and Melody are the early favourites, 5-2 at both Ladbrokes and William Hill.
From Wales and Bristol, the pair have already begun writing songs together.
The boys dazzled the judges with their own composition of Hopeful, with lyrics about their experiences of bullying.
They reduced the judges to tears and show supremo Simon Cowell pressed his golden buzzer.