Justin Bieber bounced back from a black-out on Friday to perform an impromptu sing-along with fans from a balcony outside the Paris headquarters of his record label.

The teenage pop sensation knocked himself out by running into a glass wall backstage during a free concert in the city on Thursday, and later revealed he had blacked out in his dressing room for 15 seconds.

But, after nursing a concussion and a headache overnight, Bieber was back in fine form on Friday afternoon, crooning to screaming fans from a megaphone high above the Latin Quarter streets.

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Justin Bieber serenaded fans from a balcony

He was accompanied on the songs Boyfriend, Baby and One Time by musical director and guitarist Dan Kanter as he performed at the offices of Universal.

The appearance was reminiscent of a similar scene in 2010, when Bieber sang Baby from the balcony of a Paris hotel.

Taking to Twitter.com afterwards, Bieber wrote: "Loved singing with all of you WithDanKanter - just like old times."

He also posted a link to fan footage of both the 2010 appearance and Friday's brief show.

Kanter also tweeted: "What an amazing singalong off the balcony in Paris again w/ (with) JB. We should do that every 2 years! Memories for life."