What should you do if a player who left the field to be treated returns and plays the ball without permission?

When a player leaves the field to receive treatment, they must return with the referee's permission to ensure the game is played fairly and safely. If that player then engages with the ball before receiving such permission, it is critical to address this action properly.

The correct course of action is to stop play and caution the player. This reinforces the rules of the game, emphasizing that returning to the field and participating without permission disrupts the game's flow and could jeopardize the safety of all players. By cautioning the player, the referee acknowledges the infraction, underscores the importance of following procedures, and helps maintain the game's integrity.

While other options might seem viable, they do not effectively address the rules regarding player re-entry after treatment. Ignoring the situation could set a precedent that encourages similar behavior, while simply showing a yellow card and allowing play to continue fails to properly manage the game. Substituting the player immediately could also disrupt the team's structure without addressing the initial infraction. Therefore, stopping play and issuing a caution is the correct and most professional response to uphold the spirit of the game.