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.
Cops eventually caught the man -- identifying him as 38-year-old Manuel Garcia -- and arrested him for misdemeanor assault.
Cops also arrested the man's girlfriend, 33-year-old Brittney Aplin ... saying she tried to interfere with officers while they were pursuing Garcia.
Prosecutors say they have no idea yet why Garcia decided to punch Boylan ... but the guy is facing up to a YEAR behind bars for the crime if he's convicted.
As for Aplin, she's facing up to six months in jail for her role in the incident ... and both are due in court to face the charges later this week.
The Pelicans -- who played a game two days after the altercation -- issued a statement earlier this week, saying, "We are aware of this incident but will have no further comment."
Meanwhile, the Rockets say they have banned Garcia from their games for life.