The '99 Problems' hitmaker's entourage reportedly ''piled in'' on a man after he upset the rapper's wife backstage at the London music event this weekend.
A source told the Metro newspaper: ''Someone in the entourage said something to Beyonce to really upset her.
''Jay-Z's bouncers moved in and there was a massive ruckus. Things really kicked off as his heavies all piled in on the guy.''
Meanwhile, Jay-Z and the other stars performing at the event - including Rihanna, Leona Lewis and Jessie J - were told not to make backstage demands unless they paid £1,000 for a rider, and all artists were provided with a shopping list of items they could buy to make their dressing rooms cosier.
A source told the Daily Mirror newspaper: ''The VIP artists got quite a shock when they were booked.
''They were told they were welcome to bring an entourage and their families as long as they paid for their fair share of the facilities themselves.
''To have a rider, they had to fork out £1,000 - and that's per rider.''
Despite the price tag, Jay-Z still opted for brown leather sofas, white carpets and pashminas in his backstage area.
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