Justin Bieber‘s ‘Believe’ LP may be on course to debut with sales of over 400,000, yet that hasn’t stopped the teen sensation from continuing along the promotional trail.

His latest stop? The Late Show With David Letterman.

Watch the 18 year old perform ‘Boyfriend’ after the jump…

Sigh. He still sounds like puberty in motion, yet is also making the right strides to becoming a better performer. I guess we’ll take the good with the bad.

Your thoughts?