A second day of stifling heat and humidity caused havoc at the US Open on Tuesday, prompting tournament organisers to implement special rules to provide some relief for suffering players.
With temperatures soaring towards 38 degrees amid crushing humidity, the United States Tennis Association announced that the 10-minute heat break the women players are granted between the second and third sets of their matches would be extended to the men as well.
"Upon the recommendation of the US Open medical team, the Extreme Heat Policy will be implemented immediately for men's matches," the USTA said in a statement.
"The men will be offered a 10-minute break between the third and fourth set.
"The Tournament Referee, along with the medical team, will continue to monitor on-site conditions, to determine when the Extreme Heat Policy will no longer be in effect."
One fan collapsed in the stands at the sun-exposed court 17 during Petra Kvitova's win over Yanina Wickmayer, causing the chair umpire to halt play while emergency medical personnel attended.
There were four mid-match retirements from the men's draw, though not all were put down to heat stress.
Elsewhere, fans crowded into the shady sections of the tournament's two stadiums and fanned themselves furiously while taking in the first-round action.
Organisers urged everyone attending the 50th edition of the tournament in Flushing Meadows Park to drink plenty of water and use sunscreen to protect themselves.
Yet they said they would not close the roof on either of the two stadiums due to the heat.
The new 14,000-seat Louis Armstrong Stadium does not have an air conditioning system but relies on a first-of-its-kind natural ventilation system, which will be severely put to the test.
The roofs on Arthur Ashe stadium and Louis Armstrong stadium will likely be shut on Friday, however, as rain is forecast and expected to bring relief from the heat. It could also throw a wrench in the tournament's busy schedule.
As for the players who have to cope with the sweltering conditions, it is all part of the brutal test that is the fourth and final grand slam of the year.
"It's one of the reasons the US Open is the toughest test in tennis," USTA spokesman Chris Widmaier said.
