In a game of association football (soccer), the fourth official is a match official who assists the referee in a variety of tasks, and who may be called upon to replace another match official.

Background

A game of association football is presided over by a referee, who is assisted "on field" by two assistant referees.

The fourth official is a recent addition to the officiating crew. Famous referee and administrator Ken Aston introduced the practice of having a named replacement referee in 1966, but the International Football Association Board (IFAB) did not officially create the position until 1991, and listed only a areas of responsibility. The fourth official is simply instructed to assist the referee at all times, and his duties are largely at the discretion of the referee. His usual duties can be broardly dividing into assisting functions and a replacement function (see below).

The fourth official typically has a table a short distance from the touchline between the two teams' technical areas, however his positioning is not defined by the Laws of the Game.

Assisting function

In usual practice, the fourth official assists the referee in the following ways:

• Assising with administrative functions before, during and after the match;
• Assessment of players' equipment;
• Ensuring substitutions are conducted in an orderly manner and notifying the referee of the details of the substitution;
• Acting as the contact point between the match officiating crew and any non-participants (such as stadium managers, security personnel, broadcast crews, and ball retrievers);
• Maintaining decorum in the teams' technical areas and interceding in situations where coaches, bench personnel, or substitutes become agitated;

In practice, the fourth official becomes a key member of the officiating team, who can watch the field and players and advise the Referee on situations that are going on out of his sight. The fourth official keeps an extra set of records, and helps make sure the Referee does not make a serious error such as cautioning the wrong player, or giving two cautions to the same player and forgetting to send off the player.

Replacement function

The fourth official serves as a replacement official in the event that one of the other officials (referee or assistant referees) can not continue officiating (usually through injury).

In situations where an assistant referee is unable to continue, the fourth official replaces that assistant referee. In situations where the referee is unable to continue, either the fourth official replaces the referee directly, or the senior assistant referee replaces the referee, with the fourth official in turn taking an assistant's position.

Competition rules are supposed to clarify which of these options is to occur. If for some reason it is not stated, then typically the official with the most refereeing experience (either the fourth official or the senior assistant referee) will replace the referee.