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Starpix, Amanda Schwab, Associated Press
This image released by Starpix shows singer Justin Bieber performing on the "Today" show as part of their summer concert series in Rockefeller Center, Friday, June 15, 2012 in New York.

NEW YORK — Justin Bieber had an unplugged performance at the Apollo Theater, but it wasn't intentional — a problem caused a power outage during the singing sensation's big concert.

The singer was nearing the end of a private show in front of a packed house on Monday when the power for most of the stage instruments suddenly went out.

His manager, Scooter Braun, says Bieber still managed to finish the show, serenading the crowd with his hit "Boyfriend" as they sang along.

Bieber's performance was part of a series of promotional events to promote his new album, "Believe," out Tuesday.