Justin Timberlake narrowly missed being punched in the face after a fan sneaked into a VIP area to take his photo.
The "SexyBack" singer - who was celebrating his duet with Beyonce Knowles at the New York Fashion Rocks party earlier on Saturday evening - was forced to dive for cover when a brawl got out of hand at the city's Rainbow Bar.
His bodyguard had snatched the admirer's camera phone and tried to delete the picture before the woman's friends stepped in to defend her.
Beyonce, her sister Solange and Mariah Carey screamed in terror as champagne glasses were smashed, while Rihanna and Chris Brown tried to avoid the flying glass.
Justin's bodyguard was later thrown out of the club.
A source told Britain's Daily Mirror newspaper: "It was mayhem. Justin narrowly missed being punched in the face. His bodyguard kicked off, screaming at the girl and snatching the camera off her to delete the picture."
"A huge commotion broke out with the fan's male pals who tried to protect her. Fists were flying and Justin was desperately trying to get out of the way."