Anthony Kiedis Fights With Bodyguard

Red Hot Chili Peppers singer Anthony Kiedis just threw down with a security guard outside the Four Seasons in Philadelphia -- after the hired muscle REFUSED to let Kiedis enter the hotel -- and the footage is insane.

In the footage, Kiedis approaches the hotel with his lady friend and security blocks him from entering. The security guard lunges, and a massive fight erupts.

Sources on scene said that the Rolling Stones were making their exit from the hotel at the same time Kiedis was approaching -- and the security guard thought Kiedis was just another fan.

But the mystery ... no one's saying who the bodyguard works for.

A rep for Four Seasons in Philly is denying the security guard works for the hotel. A source close to the Stones insists he doesn't work for them either ... at least not directly. 

The Stones source says it's possible the bodyguard was hired in Philly to supplement the band's regular security.