Novak Djokovic says US Open organisers must address playing conditions on Arthur Ashe Stadium, claiming the arena felt like a "sauna" during his quarter-final win over John Millman.
A New York heatwave has made for tough conditions throughout the tournament, but the humidity on Flushing Meadows' main show court has been a major talking point in the second week.
Roger Federer said he felt like he "couldn't get air" when suffering a shock defeat to Millman on Monday and Djokovic expressed similar views after beating the Australian two nights later.
What is more, the Serbian called on action to be taken by the United States Tennis Association.
"I personally have never sweated as much as I have here. It's incredible," said Djokovic.
"I mean, I have to take at least 10 shirts for every match. It's literally after two games you're soaking, you know. And Roger, you mentioned him. He never sweats that much. But we saw him a couple nights ago.
"I asked the chair umpire whether they are using some form of ventilation or air conditioning down at the court level side, and he said that he's not aware of it. I think that this tournament needs to address this, because whether it's night or day, we just don't have air down there. It feels like a sauna.
"I don't know what to add to that. Obviously, it is fantastic to have the roof. We, as players, are grateful that we have the roof, because then the rain will not interrupt the matches and matches will go on, on two courts, which is great.
"But I think that with so many players retiring that first round, first day or second day, and so many players struggling to breathe, especially on the center court ... there is no circulation of the air at all, especially court level. I think that's something to really think about, consider and address."
After reaching his 11th semi-final in New York, Djokovic will face Kei Nishikori on Friday.
