NEW YORK -- Novak Djokovic had just held serve for a commanding 5-0 lead in the fifth set when he let out a Kobe Bryant-esque scream while clenching his fist.
All Alexander Zverev could do was put his racket into his mouth and bite down in frustration. On the opposite side, Djokovic could almost taste history.
Djokovic is one win away from walking on tennis' hallowed ground. A victory over second-seeded Daniil Medvedev on Sunday would make him the first man since Rod Laver in 1969 to win the calendar Grand Slam. One more win and the best player in the world separates himself from Roger Federer and Rafael Nadal with his 21st Grand Slam victory.
Another win and Djokovic arguably stakes his claim as the greatest men's tennis player of all time. There's no argument from Zverev, who saw why Djokovic is here on the doorstep of history.
"I'm going to treat this match as it's my last one," Djokovic said of Sunday's historic final. "Because it's arguably the most important one of my career maybe. Maybe not, I don't know."
In the time that it takes Stefanos Tsitsipas to complete a bathroom break, Djokovic turned a tension-filled semifinal into a fifth-set rout, winning the first five games of the final set in 19 minutes before closing out a 4-6, 6-2, 6-4, 4-6, 6-2 win over the fourth-seeded German.
"Nobody thought anybody will do it again, what Rod Laver did," Zverev said. "I do believe that he will do it. He's breaking every single record that there is.
"If you look at the stats, if you look [at] the pure game of tennis, he's the greatest of all time. Nobody is there with him. Most weeks [as] world No. 1, most Masters 1000s titles, most likely going to be the most Grand Slams at the end of the day. And he has the chance of winning all four in the same year. How do you compete with that?"
Zverev gave Medvedev a glimpse of the lengths one has to go to in order to beat Djokovic. At 5-4 in the third set, Zverev and Djokovic engaged in an absolutely ridiculous 53-ball rally. It wasn't just the longest rally of the US Open, it was the longest in any major match Djokovic has played in this year. Zverev needed to hit a cross-court winner to end the exhausting point, which lasted a minute and 18 seconds.
Alexander Zverev beats Novak Djokovic to win the longest rally of this year's US Open.
The problem for Zverev was that Djokovic still won the game and the set. To his credit, Zverev battled back and won the fourth. But as has been his trademark style, Djokovic again punished his opponent as the match went on. He's one of the sport's greatest closers. His 32 wins in five-setters in the slams is the most by any player in history.
Djokovic almost always saves his best tennis for last, picking up his level another notch in the fifth to outdo Zverev.
"Mentally, he's the best player to ever play the game," Zverev said. "Mentally in the most important moments, I would rather play against anybody else but him."
Djokovic, though, isn't just playing the opponent on the other side of the net. With Laver watching over his shoulder in the stands, Djokovic is also dueling history.
Serena Williams saw her bid for a calendar slam derailed in the semis here to Roberta Vinci in 2015. Entering that Open, Williams tried to avoid talking about history.
"I won that year," Djokovic said of one of his three US Open titles. "I was talking to Serena. She was very emotional about everything that was going on. I can relate to what she's been going through right now. I understand it now ... I understand why she wanted to avoid all the questions about it because at the end of the day, you have to go out on the court and deliver."
Perhaps it is fitting that before Djokovic finished his late-night news conference, he cited one of Bryant's great quotes. Djokovic has long admired Bryant, and he remembered a famous line by Bryant from the 2009 NBA Finals when the Los Angeles Lakers were up 2-0 on the Orlando Magic.
"It's his famous interview where he said, 'Why should I be happy right now? Job is not done,'" Djokovic said. "... That's kind of an attitude I have. Job is not done."