For the first single off his March release My World (Part II), Justin Bieber sticks to what's worked for him pretty well so far: singing about young love. And in "Baby," the 15-year-old Canadian pop sensation has Ludacris rapping about his own first love too.

As in Bieber's previous releases, this track features his R&B vocals over a beat. "For you, I would have done whatever/ And I just can't believe we ain't together/ And I wanna play it cool/ But I'm losin' you," he sings. "I'll buy you anything/ I'll buy you any ring/ I'm in pieces/ So come and fix me/ Come and shake me till you wake me from this bad dream."

The song's chorus features the teen singing "Baby, baby, baby" repeatedly. Late in the track, Luda, who has worked with fellow pop star Jesse McCartney in the past, raps about his experience with puppy love: "When I was 13/ I had my first love/ ... She had me going crazy/ Oh, I was star-struck/ She woke me up daily/ Don't need no Starbucks."

On Monday, as the song was released to iTunes, Bieber took to Twitter, thanking his fans for helping him become such a sensation. As of Tuesday morning (January 19), the song was already #2 on the iTunes singles chart.

"Everyone please start requesting BABY feat Ludacris at your local radio stations!" he wrote. "Let's get it as our first #1 on iTunes and on Billboard!!"