THE DECISION
The player must leave the field of play within ten seconds of the substitution board being shown, usually at the nearest point on the boundary line. If the time limit is exceeded, the player must still leave as quickly as possible (no caution, unless they excessively delay the restart). Play restarts, but the substitute may only enter with the referee’s permission during the first stoppage after one minute has elapsed following the restart.
Read official Law 12 ↗