Justin Bieber Instagram, Twitter Reveal New Song 2013 'All That Matters:' Track to Follow Up 'Heartbreaker' for Music Mondays Project

Justin Bieber has revealed the second song title for his Music Mondays project.

On his Instagram yesterday (Oct. 9), the "Baby" singer posted a simple message alongside a photo of him bowing to a massive audience: "All That Mattters is next on #musicmondays lets go," he wrote, announcing the song title with relatively little fanfare.

Several hours later, Bieber reiterated the song title on his Twiter (while promoting "Heartbreaker"), writing "JUST GETTING STARTED with this One - All That Matters is next #heartbreakeronitunes."

Bieber's website -- which recently got a makeover to accommodate his Music Mondays project -- has yet to be updated with the single cover for "All That Matters."

"All That Matters" will be the second song released as a part of Bieber's Music Mondays project, wherein he will release one new song every Monday at midnight from now until Dec. 9. Music Mondays also plays into Bieber's long-anticipated music journals project. With each track Bieber releases on Monday, he will post a short journal entry of the song, describing where he was when he wrote the track.

The first track for Music Mondays was the highly anticipated, Selena Gomez-inspired single "Heartbreaker." The mature, classical pop R&B track is a slow burner, allowing for the revelatory lyrics to shine through over the simplified beats.

"All That Matters" has yet to be heard or partially teased. However, Bieber did post two snippets of songs from his Music Mondays project to Instagram and YouTube earlier this week.