Introduction

In competitive 11-a-side matches, teams are allowed to bring on up to three substitutes. The rules of the competition must state the maximum number of players allowed to be named as a substitute, which may be anywhere between three and twelve. In non-competitive matches, the use of substitutes must be determined before the match begins, except in friendly international matches, where no more than six substitutes may be brought on.

The most tired players are generally substituted, but only if their substitutes are well trained to fill in the same role, or if the formation is transformed at the same time to accommodate for the substitution.

Coaches often refrain from substituting defensive players in order not to disrupt the defensive posture of the team. Instead, they often replace ineffective attackers or unimaginative midfielders in order to freshen up the attacking posture and increase their chances of scoring.

For a team that is losing a game, a fresh striker can bring more benefit in circumventing an opposed defence line composed of relatively tired players. For a team that is winning a game, a fresh midfielder or a defender can bring more benefit in strengthening the defence against the opposition's attackers (who may be fresh substitutes themselves). In this situation, it is usually imaginative attacking flair players who are replaced by tough-tackling defensive midfielders or defenders.

Injured players may also need to be substituted. For each injured player who must be substituted, the team loses one more opportunity to influence things later in the game in their favour.

Substitutions can also be used as a time consuming tactic to hold a one-goal lead in the last minutes.