The Australian Tennis Federation and the Thermal Ergonomics Laboratory of the University of Sydney have developed a heat stress scale for the Australian Open. It consists of five gradations, which take into account four climatic factors and physiological differences between adult tennis players, juniors and wheelchair users. Thus, when the heat reaches 4.0, women and juniors will get a 10-minute break after the second set, and men after the third set. The latter is a novelty. With a value of 5.0, all matches will be suspended (with an even number of games or the end of a tiebreak), and the next ones will not be started. However, on the courts with a roof fights can be continued with the roof closed by a judge’s decision.