A man invaded the Laver Cup in London on Friday and set his arm on fire right next to the net -- just hours before Roger Federer will play his last-ever competitive tennis match on the court.
The wild scene just went down minutes ago during a match at O2 Arena -- when a guy wearing blue jeans and a T-shirt stormed the court with a lighter in his hand.
Video shot by witnesses in the stands shows the man sat down, made a fire -- and then let the flames crawl up onto his arm.