After the last successful free throw by Yellow 9, Blue 8 requests a substitution and the timer sounds his signal to communicate the request. The referees say that the substitution is not possible. Article 19.2.2: A substitution opportunity begins when: For both teams, the ball becomes dead following a successful last free throw. Article 19.2.4: A player who has become a substitute and a substitute who has become a player cannot respectively re-enter the game or leave the game until the ball becomes dead again, after a clock-running phase of the game. Outcome: Correct decision from the referees. Blue 8, who was a player, left the court and became a substitute after the personal foul was called. After the free throws he wanted to re-enter the court. Even if this is a substitution opportunity, he cannot re-enter the court as the game clock has not run since, he left the court.