What is a 'second ball' incident in a match?

A 'second ball' incident refers to a situation in a match where an additional ball enters the playing field during active gameplay and interferes with the play. This can disrupt the flow of the game, as players may inadvertently react to the presence of this extra ball. According to the Laws of the Game, if a second ball does enter the field while the match is in progress and it affects the play, the referee must stop the game, remove the second ball, and then restart it appropriately, often with a drop ball or a free kick depending on the circumstances.

The other scenarios presented do not fit the definition of a 'second ball' incident. A collision between two players, the referee dropping the ball, or a ball hitting the crossbar do not involve an external ball affecting the ongoing play and thus do not constitute a second ball situation. Understanding this concept is crucial for referees to manage the game effectively and maintain its flow.