OAKLAND, Calif. – After the Golden State Warriors advanced to the NBA Finals, All-Star guard Klay Thompson began to develop concussion-like symptoms that will force him to pass the NBA's concussion protocol test before he can be cleared to play.

Thompson was kneed in the head by Houston Rockets forward Trevor Ariza with 9:30 left in the fourth quarter of the Warriors' 104-90 deciding victory in Game 5 of the Western Conference finals. After falling to the floor in pain, Thompson was eventually replaced by Stephen Curry and went to the locker room. The Warriors stated that Thompson went through a concussion medical evaluation immediately after suffering the injury and showed no symptoms at that time.

Thompson returned to the bench before the end of the game, but began bleeding from his right ear and returned to the locker room to get stitches to close a laceration in the ear. The Warriors said he began exhibiting concussion-like symptoms after the game.

"He said he just needs a good night's sleep," said Thompson's father, former NBA player Mychal Thompson. "[He] threw up and says he feels a lot better."

Klay Thompson must complete the NBA concussion protocol before being cleared to play in the Finals, which begin on June 4. For Thompson to be cleared for full participation, he must get clearance from the Warriors' team physician who must discuss the return-to-participation process and decision with Dr. Jeffrey Kutcher, director of the NBA's concussion program.

"Once a player is diagnosed with a concussion he is then held out of all activity until he is symptom-free at rest and until he has no appreciable difference from his baseline neurological exam and his baseline score on the computerized cognitive assessment test," states the NBA's concussion protocol. "The concussed player may not return to participation until he is asymptomatic at rest and has successfully completed the NBA concussion return-to-participation exertion protocol."

The return-to-participation protocol "involves several steps of increasing exertion – from a stationary bike, to jogging, to agility work, to non-contact team drills. With each step, a player must be symptom free to move to the next step. If a player is not symptom free after a step, he stops until he is symptom free and begins again at the previous step of the protocol."

When asked if he believes Klay will complete the concussion protocol quickly, Mychal Thompson told Yahoo Sports: "Yeah, I think so, but I'm no doctor."

Thompson averaged 18.5 points, 5.5 rebounds and three assists in two regular-season games against the Cleveland Cavaliers. He has averaged 19.7 points and 4.9 rebounds and four assists in 15 postseason games. Only Curry has averaged more points per game (29.2) for the Warriors this postseason than Thompson.