Scary moment for Shareef O'Neal ... who appeared to be seriously injured during a high school basketball game Monday night when he went up for a shot and came down on his head.
Shaq's son was making his senior season debut for Crossroads High School in a game against Beverly Hills High and was lighting it up with 31 points ... until the injury.
Shareef went up in traffic for a layup, but his legs got tangled with the defenders -- and he came crashing down hard without bracing himself. You can hear the crack on the court -- and Shareef was holding his head in pain afterward.
O'Neal eventually got up but didn't go back in the game. We're told he's now in the team concussion protocol and will miss Tuesday night's game as a precaution.
Shareef is one of the top high school players in the country and has already committed to the University of Arizona.
Get well soon, man.