A man is suing skateboarding star Nyjah Huston -- after he says the 27-year-old X Games athlete beat him up during an altercation in Los Angeles earlier this summer.
Alexander Pou filed the lawsuit Wednesday -- alleging the incident happened back on June 6 after Huston and a friend went to Pou's house to retrieve an item they had left the night before.
In the suit, obtained by TMZ Sports, Pou alleges he tried to help Huston find the item ... but when their search was unsuccessful, the skateboarder "became verbally abusive.