A member of the audience at Justin Bieber's stage show in Dubai tackled the singer from behind while he was performing at a grand piano.
Bieber managed to free himself and ran to the side of the stage while security guards grabbed the intruder, who managed to knock the piano over and onto its side.
The singer later retweeted descriptions of the "mayhem".
He later tweeted: "Dubai. Nothing stops the show. 2 more to go."
Footage on YouTube shows Bieber carried on performing while security guards removed the fan and picked up the piano.
He is in the middle of a world tour called Believe which began last September and includes about 100 dates.
'Wasn't a prank'
Reports said that the globally successful 19-year-old took a three-minute break after the on-stage fracas before returning to sing Boyfriend and then Baby.
Reports said that the globally successful 19-year-old took a three-minute break after the on-stage fracas before returning to sing Boyfriend and then Baby.
His guitarist and musical director Dan Kanter later tweeted: "It wasn't a prank. Someone ran on stage during Believe and the piano got knocked off its platform. Everyone is fine. No need to worry!"
A parent of one of Bieber's fans at the Dubai gig, Steve Hoare, told the BBC that as the tickets cost about £100 each, a lot of parents were left angry afterwards.
He said: "My 16-year-old daughter said that the kids at the concert were pretty shocked by it all.
"The attacker may have been an adoring fan. But it was probably someone who was annoyed at Justin Bieber being more than two hours late, as he was the night before.
"Both nights are school nights here, so it was not clever and pretty arrogant, particularly when you play a set that is only just over an hour long."
He added that "this kind of thing doesn't happen in Dubai".
Mr Hoare said that as the region relies "so heavily on tourism", he would be interested to see "what action the authorities take".
Bieber has not been short of headlines recently. Last month he provoked fierce online criticism with his message in a guestbook at the Anne Frank Museum, saying he hoped the Holocaust victim would have been a fan.
The Canadian pop idol wrote: "Truly inspiring to be able to come here. Anne was a great girl. Hopefully she would have been a belieber."
The museum defended the star but added his comment "wasn't very sensible".