Novak Djokovic defeated John Millman 6-3 6-4 6-4 to book a semi-final place in the 2018 US Open.
Millman failed to reproduce the form he showed against Federer to send the Swiss parking, Djokovic showed class to march on.
Djokovic who missed last year’s edition due to an elbow injury will slug it out with Japan’s Kei Nishikori in the last four on Friday.
“I personally have never sweat as much as I have here. Incredible. I have to take at least 10 shirts for every match. It’s literally after two games and you’re soaking,” Djokovic said.
“I asked the chair umpire whether they are using some form of ventilation or air conditioning down at the court level, and he says that ‘he’s not aware of it’, that, you know, only what comes through the hallway type of thing.
“I think that this tournament needs to address this. I mean, because whether it’s night or day, we just don’t have air down there. It feels like sauna.”