fighting irish X/@Raw_News1st
The Boston Celtics and Dallas Mavericks weren't the only ones going head to head in the NBA finals ... a bunch of Celtics fans got into an amateur boxing match at a game 4 watch party.
Friday night's brawl broke out between two men seated near each other in the crowd at TD Garden arena in Beantown ... where Celtics fans were having a viewing party of the on-court action taking place inside American Airlines Stadium in Dallas.
Check out the vid .