NBA legend Paul Pierce has been ordered to write a $100,000 check to a security guard he called "racist" at the Conor McGregor vs. Khabib fight ... TMZ Sports has learned.
We broke the story ... a security guard at the T-Mobile Arena in Vegas sued Pierce for defamation and other things over an altercation they got into during UFC 229 in Oct. 2018.
Long story short ... Pierce called security guard Christopher Mostello "racist" -- claiming Mostello (who is white) gave him a hard time while trying to get to his seat.
Pierce's "racist" allegation was captured on video and posted by TMZ Sports.
Inhis suit, Mostello claimed it was Paul who was acting inappropriately that night -- saying Pierce had gotten aggressive and physical with a female security supervisor -- and Mostello was only doing his job.
Mostello claimed his reputation took a serious hit because of the altercation and Pierce's accusations -- and he's been subjected to public embarrassment, harassment and ridicule.