New Year's Eve 2013 Photos: Stars Ring in the New Year
Justin Bieber performs on Dick Clark's New Year's Rockin' Eve on December 31, 2012 in Los Angeles, California.

Pop superstar teases upcoming acoustic album with stripped-down take on "Boyfriend."

Justin Bieber capped off a huge 2012 by performing a trio of "Believe" singles on "Dick Clark's New Year's Rockin' Eve" on Monday night (Dec. 31) and, at one point, showing off his 18-year-old chiseled abs by momentarily lifting his shirt.

All three singles from Bieber's latest LP, which was released last June, got the "Rockin' Eve" treatment when the pop superstar took the stage in Hollywood: "Boyfriend" was performed as a stripped-down ballad with only an acoustic guitar player onstage with the Biebs, while "Beauty and a Beat" and "As Long As You Love Me" were rolled out with flashing lights, backup dancers and some lock-step choreography from young Justin.

Although Nicki Minaj did not show up to handle her verse on "Beauty," G.O.O.D. Music MC Big Sean was on hand to join Bieber for "As Long As You Love Me," which climbed into the Top 10 of the Hot 100 last year.

Along with the three performances by Bieber, "Dick Clark's New Year's Rockin' Eve" included songs from a handful of artists connected to Bieber's manager Scooter Braun, including U.K. boy band The Wanted, K-pop sensation PSY and Canadian pop starlet Carly Rae Jepsen. Bieber's acoustic take on "Boyfriend" precedes a full acoustic album that Bieber plans to release in 2013; last month, the singer teased the track list on Twitter, and said that two new songs would also make it onto the disc.

HAPPY NEW YEAR 2013!
TAYLOR SWIFT
• PHOTOS: Stars on New Year's Eve
• VIDEO: Justin Bieber NYE Preview
• VIDEO: Taylor Swift Performs, Kisses Harry Styles in Times Sq.
• VIDEO: PSY Celebrates in 'Style'
• TWEETS: Stars Ring in 2013
• INTERVIEW: Ryan Seacrest Talks 'Rockin' Eve,' Dick Clark
• VIDEO: Flo Rida NYE Preview
• VIDEO: OneRepublic NYE Preview
JAY-Z
• REVIEW: Jay-Z & Coldplay's Brooklyn NYE Show
• VIDEO: The Wanted NYE Preview
• VIDEO: Ellie Goulding Q&A
• VIDEO: Justin Bieber Rocks NYE
• PHOTOS: Inside Lake Tahoe's SnowGlobe 2012 Festival
• VIDEO: Greyson Chance Q&A
BACKSTAGE: 'Dick Clark's New Year's Rockin' Eve'