Novak Djokovic gets locked in an intense rally with John Millman and Djokovic is able to secure the point is captured on the AI IBM Highlight. (0:51)

NEW YORK -- Well that was weird.

Novak Djokovic and John Millman were sweating buckets all night in their quarterfinal clash at the US Open. They changed outfits at random times (without a code violation), swapped socks (not with each other) and Djokovic was given some fluids, courtesy of his loved ones in his players' box.

Chalk it up to another case of the suffocating New York air and a couple of drenched dudes.

Here's a timeline of what unfolded Wednesday amid Djokovic's 6-3, 6-4, 6-4 win:

Set two, 2-1 Djokovic: Djokovic was looking at his box. His people gestured to him and said, "Do you want another one," pointing at a bottle of water and a white energy drink. It seemed as if Djokovic wanted something else, but he did not engage in a conversation.

"Can I write it down?" Djokovic asked, smiling.

The umpire presumably denied the request (although it was not caught on camera). Djokovic walked back to the baseline, still smiling and shaking his head.

He then pointed to the baseline and said, "It's so wet here." He wasn't smiling anymore.

A ball person ran over with a towel and wiped the water/sweat from the court.

Set two, 2-2: Millman asked to change his clothes during a non-changeover. In tennis, you change sides only during odd games. Millman confronted Djokovic and asked for his blessing. "Can I go change my clothes now?" he said in an act of good sportsmanship. "They are saying I can only change now."

Djokovic smiled at him and said, "I'm fine to have a little rest." In other words, take your time, mate. Djokovic enjoyed the break.

Ah, no shirt. Amid another crazy humid day in New York, Novak Djokovic let himself air out for a little while. Julian Finney/Getty Images

The umpire then announced, "Ladies and gentleman, due to humid conditions, Millman is going to change his attire."

He ran to the locker room with a fresh pair of shoes and clothes in hand. A few minutes later, he returned with those shoes and clothes on his body.

In his on-court interview, Djokovic said the break was a win-win. Millman needed a change of clothes, Djokovic needed a rest and they both got what they wanted.

The USTA released a statement explaining the strange set of events.

"John Millman approached the chair umpire to note his excessive sweating and the moisture it was leaving on the court. The umpire determined that the surface was dangerous enough to invoke the 'Equipment out of Adjustment' rule in the ITF Duties and Procedures of officials."

While Millman was in the locker room, Djokovic's wife, Jelena, ran from her seat, down the stairs, and with the help of an official, gestured to Djokovic. But he was too comfortable in his changeover chair.

Instead, a ball person got two bottles -- one water and one white energy drink -- from Djokovic's box and brought it to him.

Jelena then passed on what looked like a small white box. Djokovic put it inside his bag. In his news conference, Djokovic refused to answer questions on what exactly was in the box.

Set two: 4-3 (Djokovic): The players took a break and Djokovic removed his shoes and socks, then used a towel to wipe his feet.

The umpire was overheard saying, "Do we need to wipe the baseline?" But this time, they did not. Djokovic, though, continued to wipe his feet.

When he was done, he put on a fresh pair of socks and shoes and play resumed.

End of set two, 6-3, 6-4 (Djokovic): During another stop in play, Millman left to change again, this time with an official in tow. Millman returned with an all-black attire.

Before play resumed, Djokovic, sitting in his chair, drinking his liquids, asked the umpire, "Do you have ACs on the grounds?"

The umpire said, "Why do you ask?" Oddly enough, it wasn't a rhetorical question.

Novak Djokovic and John Millman came to an understanding that bonus timeouts would be allowed. Matthew Stockman/Getty Images

Djokovic said, "No, I am just curious. Are there just ACs in the corridors or up above and on the grounds?"

The umpire's response wasn't caught on camera, but Djokovic was listening closely, nodding his head, conceding any dreams of cool air would have to wait.

Third set: No unusual breaks, no complaints. Djokovic advanced to the semifinals and afterward was understandably giddy and tired at the same time.

On-court interview: Djokovic was honest in his assessment. "I was struggling, he was struggling, we were all sweating. We were changing shirts, and shorts. You survive on the court in a way and thrive with a win. Not easy conditions to play in for either players. He was apologizing actually. He felt very sorry he had to leave the court and change. I said, 'Man, it's OK, go ahead, I am feeling OK sitting down and relaxing.' I needed that break."

Then in his news conference: Djokovic shed some light on why he asked about air conditioning. "The umpire said he was unaware of such a thing. I think it's something that needs to be addressed. There is no air down there; it's like a sauna."

Finally, one media member asked the one question everyone wanted to know: "Is the locker room stinkier than usual?"

"What happens in locker room stays in locker room," Djokovic quipped.

And that was that.