'Yellow Raincoat,' a new acoustic song from Justin Bieber's 'Believe Acoustic,' which lands on Jan. 29, has leaked. It's a moody and contemplative song, and it's Biebs at his most mature.

He's lost in thought and melancholic as he muses about "putting on my raincoat, my yellow raincoat, baby it's keeping me dry." He could very well be mining his personal life as source material for the song, which is clearly about a girl. We think her name is Selena Gomez.

The Biebs sings over a lilting acoustic guitar melody as he offers his best impression of Usher. It sounds like he lifted inspiration from his R&B mentor on this song. If you didn't know it was the Biebs before you listened to it, you might not have recognized him. It's that much of a stylistic left turn and a leap forward for him.

It's delicate, fragile and vulnerable, not something we normally associate with the cocky and confident singer.

Da Biebs also laments his station in life, as though being famous and the object of so many Beliebers' affection is stressing him out a bit and he needs some sort of respite. It's quite an honest song, lyrically speaking.

These lines are what convince us he's singing about Sel: "Whenever I do have it, do I have it, want this to face me / Whenever I do have it, do I want this thing to make me / Cause the fame, and the money, and the girl will drive you crazy."

If the lyrics are to be given any credence, this sounds like a Sel song, undoubtedly!

There's also a bit of a world music tone the guitar as the song fades out, and there's also some sweet "do do do" harmonizing. But overall this is the saddest and most musically pensive Bieber ballad we've ever heard.

Beliebers, what do you think? Do you like the slow pace and ruminative tone? Or do you prefer dancefloor Biebs?