What should a referee do if a player receives a second yellow card in one match?

When a player receives a second yellow card in one match, it results in a red card, which means the player must be sent off the field. This is an essential rule in soccer designed to maintain the integrity of the game and to enforce discipline among players. The first yellow card serves as a warning to the player about their conduct, while the second yellow signifies that their actions have warranted a more severe punishment, thus leading to expulsion from the match.

The referee must then document the incident and ensure that the player leaves the vicinity of the field. This action is crucial not only for the enforcement of rules but also for the safety and fairness of the match, as it reinforces to all players the importance of adhering to the laws of the game. The other options, such as ignoring the situation or using a green card—which is not implemented in most leagues—would undermine the authority of the referee and the rules of the game. Verbally warning the player is insufficient in this case, as the appropriate disciplinary action must be taken based on the player's repeated offenses.