The growing pains of a teen idol

Bieber offers to 'be a gentleman' in his latest single

Justin Bieber has dropped a new track, "Boyfriend", his first since he reached adulthood earlier this month. And one thing's for sure: he wants us to know that he is all grown up.

The bubblegum pop that helped make him the world's most famous teenager has been replaced by edgier production, deeper vocals and an offer to "be a gentleman, anything you want". There's even a hint that he has censored a rude word (edgy!).

It's clear Bieber covets Justin Timberlake's position as the slick prince of pop adored by girls and women alike (which is free since Timberlake decided to concentrate on movies). But it's hard for tween idols to graduate beyond bedroom walls and locker doors to the next stage.

We can't help thinking it would be easier for the Biebs to shake off his boyish image if he didn't still look about 12-years old.