A New Orleans Pelicans assistant coach was brutally socked in the face by a fan after a game last weekend ... and the violent blow was all caught on video.
After the Pelicans lost to the Houston Rockets in Texas on Saturday ... a fan near the court reared back and punched N.O. assistant coach Joe Boylan in the face -- hitting him HARD.
You can see in the video ... Boylan -- who didn't appear to do anything to provoke the man -- flew back and nearly crumpled to the ground.
Immediately, Boylan and other people near the scene directed cops toward the fan as the guy tried to make a break for it.