We're getting different versions of what incited Orlando, and people are taking sides. One account is Justin extended his hand to Orlando, who refused it, and when Justin asked what's your problem ... Orlando mentioned Miranda. Justin then tried to walk away and that's when Orlando swung.

A second version -- Justin said something to the effect of, I had sex with your wife ... and THEN Orlando swung . . . Orlando was in Cipriani restaurant which was packed with celebs, including Paris Hilton, and Diddy.