A taekwondo competitor from the Central African Republic was rushed to hospital on Friday after being knocked out during a preliminary bout.
Bertrand Gbongou Liango was kicked in the side of the head by Tuncay Caliskan of Austria during their 68kg match.
The 22-year-old fell face-down onto the mat unconscious and lay motionless while being counted out.
Liango, who was leading 4-1 in the third and final round of his bout, has undergone tests at Tzanio Hospital.
In Taekwondo, competitors score points by kicking or punching their opponents.
They are allowed to punch only the body, but can kick their opponent's head.
Blows to the head count for two points, and a blow to the body is worth one point.
Competitors wear padded headgear and chest and abdomen protectors.