Oklahoma City Thunder guard Shai Gilgeous-Alexander has been placed in the NBA's concussion protocol and is out indefinitely, the team announced Thursday.

Gilgeous-Alexander suffered the concussion after two common fouls late in Wednesday's loss to the Houston Rockets, a game in which he scored a season-high 39 points.

There is no timetable for his return; he will have to clear a series of steps to ensure he is symptom-free before resuming basketball activities.

Gilgeous-Alexander, 23, is averaging 21.2 points, 5.1 rebounds and 4.5 assists this season. He signed a 5-year, $172 million extension with the Thunder this summer.