Golden State Warriors Klay Thompson Out Indefinitely After Concussion Diagnosis

OAKLAND, CA - MAY 27:  Klay Thompson #11 of the Golden State Warriors is injured in the fourth quarter against the Houston Ro
OAKLAND, CA - MAY 27: Klay Thompson #11 of the Golden State Warriors is injured in the fourth quarter against the Houston Rockets during game five of the Western Conference Finals of the 2015 NBA Playoffs at ORACLE Arena on May 27, 2015 in Oakland, California. NOTE TO USER: User expressly acknowledges and agrees that, by downloading and or using this photograph, user is consenting to the terms and conditions of Getty Images License Agreement. (Photo by Ezra Shaw/Getty Images)

Golden State Warriors guard Klay Thompson has been diagnosed with a concussion after suffering a blow to the head during Wednesday night's Western Conference Finals game, as first reported by ESPN's Ethan Strauss.

In a short statement, the Warriors wrote:

Following extensive examinations over the last two days – including neurological tests earlier this morning – Warriors’ guard Klay Thompson has been diagnosed with a concussion. He will not return to the court until he is symptom-free and cleared under the NBA’s concussion protocol guidelines. He will be evaluated daily and there is no timetable for his return.

During the fourth quarter of Game 5 against the Houston Rockets, Thompson was hit by a flying knee belonging to Rockets forward Trevor Ariza.

Blood began running from Thompson's right ear, and he was removed from the game. Team doctors put him through concussion tests, and although he was cleared to re-enter at the time, Thompson began feeling ill.

"After the game [Thompson] began to not feel well and developed concussion-like symptoms. He will continue to be evaluated by the team's medical staff tonight," the Warriors said in a post-game statement.

On Thursday, Thompson's father told ESPN Radio's "Mike & Mike" that his son wasn't able to drive home from the arena after the game and vomited "a couple times" upon returning home.

USA Today reported Friday morning that Thompson's agent, Bill Duffy, said that he didn't have a concussion. A visit with a neurologist on Friday, however, provided Thompson with a concussion diagnosis.

As part of the NBA's concussion policy, Thompson will have to go through the league's return-to-participation protocol. To return, he must go through a range of exertion tests symptom-free, starting with a stationary bike, moving up to to jogging and then to non-contact team drills.

The final call on Thompson's status will involve the NBA's own doctors as well:

While the final return-to participation decision is to be made by the player’s team physician, the team physician must discuss the return-to-participation process and decision with Dr. Jeffrey Kutcher, the Director of the NBA’s Concussion Program, prior to the player being cleared for full participation in NBA Basketball.

With five days until the start of the NBA Finals, there's a very real possibility the Warriors may have to start their series against the Cleveland Cavaliers without their second-best player.