The ATP men's tennis tour will introduce an extreme heat policy from 2026 after criticism from players who sweltered through some tournaments this year.
The move brings the ATP into line with the women's WTA tour, which has a long-standing policy, and sports such as Formula One which has its own measures to protect drivers.
In October, Danish tennis star Holger Rune called temperatures of more than 30C and humidity soaring past 80 percent at the Shanghai Masters "brutal".
"Do you want a player to die on court?" Rune was heard to ask as he wilted in the fierce conditions.
The ATP has now acted, saying on Monday it was "strengthening protections for players competing in extreme conditions".
The new rules are based on the Wet Bulb Globe Temperature (WBGT), which measures air temperature, humidity, wind speed and other factors to estimate heat stress.
Under the measures, a player can request a 10-minute cooling break in best-of-three singles matches if the WBGT reaches 30.1 degrees or higher during the first two sets.
Play will be suspended when the WBGT exceeds 32.2 degrees.
"The new heat rule provides a structured, medically supported approach to managing extreme heat, with the objective of safeguarding player health," the ATP said.
It added it will "also improve conditions for spectators, officials, ball persons and tournament staff".
The rules do not apply to the four Grand Slams, which have their own policies.
Previously, decisions over weather conditions, including heat, were down to the on-site ATP supervisor in coordination with medical teams and local organisers.
The planet is on track to log its second hottest year on record in 2025, Europe's global warming monitor said last week.
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