The Chicago Cubs fan who was knocked out cold after the World Series was running his mouth to an Indians fan -- and even DARED the Cleveland guy to punch him ... so says the man who shot the video.
We spoke with Chris Vallimont ... who says he pulled out his phone and started to record after he saw the two men cussing at each other right outside Progressive Field.
"The Cubs fan said, 'You guys just blew a 3-1 lead, f**k you.'"
The Indians fan shot back, "Fight me, p****."
The Cubs fan replied, "Hit me now, I dare you."
The Indians fan accepted the challenge and blasted the Cubs fan in the face -- and then immediately fled from the scene while the Cubs fan laid on the ground unconscious ... so says Vallimont.
"He probably didn't move for about 12 minutes."
Cops and emergency personnel rushed to the scene and the Cubs fan was hospitalized.
The Indians fan has still not been identified -- but cops are investigating.