What is the correct procedure for a player substitution during a match?

The correct procedure for a player substitution during a match requires that the referee signals before the substitute comes onto the field. This ensures that the substitution is officially recognized and that the match can be conducted in an orderly manner. The referee's signal alerts both teams and the players on the field that a change is about to occur, allowing for an appropriate pause in play if necessary and maintaining the integrity of the match.

This procedure is critical in maintaining the flow of the game and ensuring that all players are ready for the change. It helps prevent confusion and potential issues, such as players or substitutes intermingling or disrupting the flow of play. Following this procedure also upholds the authority of the referee, which is essential in facilitating smooth gameplay.

In contrast, allowing a substitute to enter without notifying the referee undermines the structure of the match. A player leaving the field after the substitute has already entered would create confusion regarding player counts and positions, while permitting substitutes to enter at any line on the field would violate established rules that dictate specific locations for substitutions, typically at the halfway line during stoppages of play. By adhering to the proper signal procedure, the game maintains its order and decorum.