Kevin Garnett vs. Carmelo Anthony Postgame Clash -- THE VIDEO

TMZ has obtained exclusive VIDEO of the postgame screaming match between Kevin Garnett and Carmelo Anthony following Monday night's Celtics vs. Knicks game ... and it's clear both guys were ready to fight.

The incident went down in front of the Celtics team bus inside Madison Square Garden -- just a short time after things got physical between the two NBA superstars on the court.

In the video, both men can be seen yelling and approaching each other aggressively as security scrambles to keep them apart.

It's unclear exactly what the guys were saying to each other -- but we definitely heard someone use the n-word a couple of times.

Eventually, security was able to separate the big men ... and KG boarded the team bus.

After the game, Anthony told reporters it all started when Garnett spewed some trash talk during the game that "crossed a line."

"There’s certain things that you just don’t say to men, another man,” Anthony said.