Oklahoma City Thunder shooting guard Terrance Ferguson left Sunday's exhibition game against the Atlanta Hawks in the first quarter with concussion-like symptoms after taking an inadvertent elbow to the head from Alex Len. Now, Ferguson has been placed in the NBA's concussion protocol program.

Ferguson will have to clear the league's concussion protocol before taking the court again. Aspects of this process include a series of cognitive and physical examinations.

Via FanSided:

After the diagnosis of a concussion, the player is removed from the game immediately and monitored to ensure his safety and to abate symptoms as best as the team and player can.

Following 24 hours, the player may then begin the return-to-play process, provided they have not shown any symptoms. The player must then complete a series of exercises of increasing difficulty and display that he is at his baseline testing and without concussion symptoms after each test.

Players in the concussion protocol program must complete a series of increasingly difficult workouts, including stationary biking, jogging, agility drills, and non-contact team drills. A player cannot advance stages while still displaying concussion-like symptoms.

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While there is no timetable set for Ferguson's return at this time, there is no doubt he'll be itching to get back on the floor.

Ferguson, now 20 years of age, made 61 appearances with the Thunder last season (12 starts), racking up averages of 3.1 points on 41.4 percent shooting from the field (33.3 percent from beyond the arc) in 12.5 minutes per outing. He's slated to see a lot of time with Andre Roberson still hurting.

The Thunder will be back in action on Tuesday night, when they'll welcome the Milwaukee Bucks to Chesapeake Energy Arena. Tip-off is set for 8:00 p.m. ET with NBA TV having live broadcast coverage.