WATCH: Justin Bieber Serenades Fans Outside The Tonight Show

WATCH: Justin Bieber Serenades Fans Outside The Tonight Show

Justin Bieber is a smooth criminal! The singer performed impromptu acoustic version of 'Boyfriend' to his dedicated fans following his appearance on The Tonight Show With Jay Leno.

Bieber arrived at the Los Angeles studio yesterday to appear on the talk show but before heading in he parked up his customised Mercedes Benz mini-van and busted out the track.

Beliebers hearts melted as the young star began to perfom 'Boyfriend', backed by his guitarist and musical director Dan Kanter.

"After we filmed we played acoustic for all the fans waiting outside the NBC gates. Great to see how much JB appreciates his fans," Dan tweeted after.

Justin later added: "Heck yes. played for them. #withdankanter."

Earlier this week, Justin confirmed that he will release 'As Long As You Love Me' as his next single to be taken from album Believe.

The second official cut to be lifted from Believe features US rapper Big Sean and will debut on radio stations next month, reports Billboard. 'As Long As You Love Me' was originally released as a promotional track in support of Bieber's new album late last year.

Justin Bieber's new album Believe may have only been released just under two weeks ago but already it has become the biggest selling album of the year so far in the US.

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