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Oakland, CA (SportsNetwork.com) - Golden State Warriors guard Klay Thompson has been diagnosed with a concussion, the team announced Friday.

Thompson will not return to the court until he goes through the NBA's concussion protocol, so there is currently no timetable for his return.

He suffered the injury during Game 5 of the Western Conference finals when Rockets forward Trevor Ariza landed a flying knee to his head.

An All-Star for the first time this season, Thompson could miss the start of the NBA Finals against the Cleveland Cavaliers. The series begins Thursday in Oakland, California.

The 25-year-old Thompson averaged 21.7 points, 3.2 rebounds and 2.9 assists in 77 games this season. He has averaged 19.7 points, 3.7 rebounds and 2.9 assists this postseason.