Jack Duff, 13, and Cormac Connell, 14, were the first of the programme's young hopefuls to take to the stage, and immediately won over judge Alesha Dixon with their Irish charm.
The pair sang an acoustic version of Little Talk by Of Monsters and Men, which panellist Amanda Holden described as 'fabulous.'
Their rendition earned then a standing ovation from the Britain's Got Talent audience.
Alesha told them: "You're so loveable. Your voice is beautiful, I think you've got great potential and I think you should be proud today guys."
It's sort of One Direction meets Simon and Garfunkel.
David Walliams to Jack and Cormac
Dance troupe Pre-Skool - made up of children aged five to eight - also impressed the judges, as they were inspired to follow in their siblings' footsteps.
The youngsters' relatives appeared in last year's contest as part of the dance troop Nu Sxool.
Six-year-old Seren Evans told the judges prior to the audition: "We got together because our brothers and sisters Nu Sxool got to the finals of Britain's Got Talent in 2012.
"We just saw them on the TV and said, 'Why don't we have a go at that?'," said the youngster, whose sister was in last year's BGT.
After their performance, judge David Walliams told them: "I thought, I really hope their dancing lives up to how cute they are, and it did. It was fantastic."
Amanda added: "You should be so proud of yourselves. Well done."
What made it special was that confidence.
Simon Cowell to Youth Creation
Youth Creation also brought dancing fun to the stage with judge Simon Cowell telling them: "You lit up this room, totally lit it up."
The school children - aged seven to fourteen - received four yes votes from the judging panel.
Finishing the show was 19-year-old student Rosie O'Sullivan, whose rendition of This is a Man's World earned her a standing ovation from all four judges.
Simon described her audition as 'absolutely bloody fantastic.'
He added: "You have a really throwback authentic soul voice, amazing."
"I just think you're amazing, well done," said Alesha.