Chris Brown's got 99 problems - and Jay-Z's a big one.
The hip-hop powerhouse, who rapped "99 Problems," was enraged when he heard that Brown allegedly beat up Rihanna, the R&B star whom Jay-Z discovered and mentored.
"He hit the roof," a source close to him told Us Weekly. "Chris is a walking dead man. He messed with the wrong crew."
Jay-Z has long been protective of Rihanna, the 20-year-old Barbadian beauty he helped make a star.
In 2007, Rihanna - whose song "Umbrella" was burning up the charts - acknowledged that Jay-Z had to give the OK before any guy would approach her.
"I just found out from a mutual friend that guys will talk to Jay first before they try to approach me," Rihanna told People magazine. "He's very protective. Jay has my best interests in mind.
"If it's a good guy, I know Jay won't shut him down. But if he's not, Jay will be, like, 'No, no, no.' "