Updated

Browns offensive lineman Ryan Miller has begun the NFL's concussion protocol, a day after he was knocked unconscious during practice.

Miller was rushed to the Cleveland Clinic on Saturday after his frightening injury brought the Browns' indoor workout to a standstill. The 6-foot-7, 320-pounder will be monitored by the medical staff and must pass a series of tests before he can return to the field.

Miller was taking part in one-on-one blocking drills when he dropped after making contact with his helmet. He lay motionless for several minutes, and his teammates huddled around him in prayer as he was immobilized and strapped to a backboard. The Browns initially feared Miller had suffered a devastating injury, and were relieved to learn he was responsive and moving his limbs.

The Browns drafted Miller in the fifth round last year.