Jay Z -- Smokes Every Other Celeb On the Strip for Fight Night (TMZ TV)

Real bad news for Chris Brown ... Jay Z's hosting a Las Vegas bash the night of Mayweather-Pacquiao -- which means Chris, Nicki Minaj, and every other celeb can pack up their party balloons and go home.

Only problem for non-celebs ... it'll cost ya $50k for a table at Jay's party! So, don't torch that Dennis Rodman invite just yet.