Section 4: Players & Officials
Number of players (Law 3, Section 1). A match is played by two teams of a maximum of five players each, one of whom must be the goalkeeper. A match may not start, and may not resume once stopped, if either team has fewer than three players.
Substitutions (Law 3, Sections 2 and 4). An unlimited number of substitutions may be made. In an official competition organised under the auspices of FIFA, a confederation or a national FA, a maximum of nine substitutes may be used. A substitution ("flying substitution") may be made at any time, whether the ball is in play or not, except during a timeout; the player being replaced must leave via their own team's substitution zone before the substitute enters through that same zone.
Team captain (Law 3, Section 12). Each team must have a captain who wears an identifying armband; the captain has no special status or privileges under the Laws but carries a degree of responsibility for their team's conduct.
Sent-off players (Law 3, Section 8). A named substitute may replace a player sent off only after two minutes of playing time have elapsed following the sending-off, unless a goal is scored by either team first, in which case specific numerical-reduction rules set out in Law 3 apply.
The referees (Law 5, Sections 1 and 5). Each match is controlled by two on-pitch officials — the referee and the second referee — who have full authority to enforce the Futsal Laws of the Game. A second referee is mandatory for international matches. The referees' decisions on facts connected with play, including whether a goal is scored and the result of the match, are final.
Other match officials (Law 6, Sections 1 and 3). Up to three further officials may be appointed: a third referee, a fourth referee, and a timekeeper. They are positioned off the pitch, level with the halfway line, on the same side as the substitution zones. For international matches, a third referee and a timekeeper are mandatory.
Video support (Law 5, Section 7). Where FIFA has granted written permission and the competition has met all implementation requirements, a team's head coach may challenge a referee decision on goal/no goal, penalty kick/no penalty kick, a direct red card, or mistaken identity. The on-pitch referees review the footage themselves, and the original decision stands unless the replay shows a "clear and obvious error" or a "serious missed incident."