Men's singles players at the Australian Open will be permitted 10-minute breaks if temperatures at next month's Grand Slam reach hazardous levels.
Organisers have unveiled a "more extensive" Extreme Heat Policy after temperatures in the shade approached 40C during the 2018 tournament.
A 10-minute break was already in place for women's and junior singles, plus a 15-minute break for wheelchair singles.
The Australian Open gets under way in Melbourne on 14 January.
Tournament director Craig Tiley said the wellbeing of players was the "utmost priority".
Under the new policy, if a reading of 4.0 is recorded on the Australian Open Heat Stress Scale during a men's singles match, a 10-minute break will be allowed after the third set.
If the reading occurs during a women's or junior singles match, this break will take place between the second and third sets, as will the 15-minute break in wheelchair singles.
If a reading of 5.0 is recorded, the tournament referee can suspend play.
Other changes to the policy for 2019 include more comprehensive measuring of weather conditions and an increase in measuring devices across Melbourne Park.
"The AO Heat Stress Scale takes advantage of the latest medical research into the effects of heat on the human body including the maximum heat stress an athlete can safely withstand, the sweat rate of that person and their core temperature," said Dr Carolyn Broderick, Tennis Australia's chief medical officer.
"The scale also accounts for the physiological variances between adults, wheelchair and junior athletes while also taking into account the four climate factors - air temperature, radiant heat or the strength of the sun, humidity and wind speed - which affect a player's ability to disperse heat from their body."