The four piece boy group were a last minute replacement in tonight's line up, having originally been set to appear later on in the week.
But they managed to pull off their performance under pressure, singing a mash up of Cutting Crew's I Just Died In Your Arms Tonight and Tinie Tempah's Written In The Stars.
Alesha Dixon said: "I love you guys! Everything about you just works, the styling on point, your voice is sick, your rapping is heavy! You guys could get signed today!"
Amanda Holden said: "I loved it, it was sick. It was really, really good. You put cool back on the map."
Simon Cowell raved: "Being a star in the music business is more than just a voice. You gotta have charisma, you gotta have chemistry. I thought your choices of songs were brilliant.
"There's a gap in the market for you right now. We've had Take That, East 17, your vocals were brilliant."
David Walliams said: "It was sick, it was fierce. I know where you're coming from, Alesha."