Grammy Award-winning pop star Lorde has been named the most powerful minor in music after topping Billboard magazine's 21 Under 21 list.

The Royals hitmaker, 17, beat out fellow Antipodeans 5 Seconds of Summer to land the title, which ranks the hottest young stars of the year.

Justin Bieber places third on the countdown, with Dutch electronic Dj/producer Martin Garrix and girl group Fifth Harmony rounding out the top five.

Lorde follows the members of One Direction, who topped the poll last year (13).