Multiple outlets describe how referees at the World Cup must match the physical demands placed on players while managing the pressure of split-second decisions. Coverage highlights that referees face major environmental changes across host cities, including Miami’s high humidity and Mexico City’s high altitude, which can affect breathing and stamina. One report notes that an official may work in humid conditions one match and then officiate at more than 2,200 metres above sea level in the next, requiring rapid adjustment to different stresses. The articles also emphasize the role of referees’ positioning during key moments: when matches hinge on late, fine margins, the referee is expected to be in the correct location to observe incidents accurately and apply the rules. Together, the sources portray officiating as a demanding “hidden” component of tournament performance, combining physical endurance, mobility, and judgment under varying conditions that can influence both play and decision-making.