Justin Bieber and One Direction have been named as the most powerful young acts in music today.

Bieber came out top in Billboard's annual 21 Under 21 list, which is compiled to find the biggest hitting acts aged under 21.

One Direction meanwhile came in second place, despite their growing reputation as the biggest band on the planet.

In third place on the list is singer and new X Factor USA judge Demi Lovato, with American Idol's Scotty McCreery and rapper Mac Miller completing the top five.

Other notable names on the list include X Factor UK graduate Cher Lloyd, who is placed at No.8, whilst Miley Cyrus ranks at No.18.