Paul Pierce involved in altercation with security guard at McGregor vs. Nurmagomedov fight, faces lawsuit

Pierce looking like he's about to knock the Truth out of a security guard

NBA legend Paul Pierce is being sued over an altercation with a security guard in the stands at the Conor McGregor vs. Khabib Nurmagomedov fight ... TMZ Sports has learned.

Mostello claims he was told Pierce grabbed the woman by the arms and pushed her to the side -- so he stepped in front of Paul to try and stop him.
But, Mostello claims Paul didn't stop -- instead Paul screamed "F*ck you" and accused Mostello of being a racist.

In the suit, filed by attorney Jesse Sbaih, Mostello accuses Pierce of defamation and intentional infliction of emotional distress. He's demanding more than $15,000 in damages plus attorney's fees and other costs.

The security guard was not happy about being called a racist. Pierce hasn't responded to the report yet. At first when I read the headline on TMZ, I thought Pierce actually got into a fight. $15k to Pierce is like $10 to most of us. I'm sure he's not losing sleep over this. We'll let you know if more details come to light, like why did Pierce think the security guard was being racist, or what started the whole thing.