NEW YORK — Nick Kyrgios promised he’d put on a show. And against the defending champion Daniil Medvedev, the US Open was his stage. He said it took 27 years of perseverance and readjustment to be able to put together that four-set dismantling of the world number one.

Kyrgios has always had a love-hate relationship with tennis. For all the box office moments and matches where he has swiped away an opponent, there have been other occasions where he has lost his cool, or looked uninterested.

But it finally clicked, and after reaching the final in Wimbledon, Kyrgios may well be the favorite to win it all in Flushing Meadows. Playing a perfect match in tennis is a Sisyphean task, but Kyrgios is reaching the level where when he’s locked in, he’s unbeatable.

“I’m just trying to not let people down,” Kyrgios said after beating Medvedev. “I was in this press conference room a while back and I lost in the third round, it was the worst feeling because I’ve just got so much expectation. I’m finally able to show it now. I feel like I’ve been working really hard. I’ve just got a lot of motivation at the moment.”

It all came together against Medvedev. Afterwards he said to the crowd: “I’m just glad I’m finally able to show New York my talent. I haven’t had too many great trips here.”

They’d witnessed a two hour, 53 minute match which included the complete Kyrgios repertoire: the lethal serve, deft backhand slices, the rocket forehand, dabs of petulance and a moment many had never seen before in a match.

No wonder he’s likely the hottest ticket in town now that Serena’s gone. You can’t take your eyes off him. It feels like the crowd is waiting for their next Instagram-able moment, whether it’s a shot from the heavens or Kyrgios losing his cool.

During the match he smashed his racket to the ground face-down twice, boomed one loose ball against the back wall a few inches below spectators, was hit with a warning for audible obscenity and argued with the chair umpire over the shot clock continually running on serve when he was trying to wipe the sweat off his hands.

That behavior could be cause for a crowd to turn against a player. But instead, whenever he waved his arms upwards towards the packed Arthur Ashe Stadium on break point, the crowd responded with a crescendo of noise. Medvedev imitated him at stages, but didn’t get quite as much of a response.

In an arena which has resembled a heavyweight boxing crowd at stages throughout the tournament — the player walk-ons, the chest-reverberating response to incredible shots or valuable points, the celebrity attention, the playlist — Kyrgios is at home.

But it’s his home back in Australia which he frequently references. Even before this Slam he was talking about the win-win situation he finds himself in: If he manages to string together victories then all good; if he loses then he gets to go home. He’s talked about being away for four months, and wanting to put together a good run here to make his team proud.

The question is, why now? Why, at 27 years old, has Kyrgios suddenly become so good and built previously elusive consistency? Prior to this summer, his greatest returns in singles were quarterfinal finishes in 2014 Wimbledon and the 2015 Australian Open. But in the last two months he lost to Novak Djokovic in the Wimbledon final, and knocked the world No. 1 out of the US Open.

“I felt like when I was really struggling mentally, I was very selfish,” Kyrgios said. “I felt like, I feel bad, I don’t want to play. Then I looked at the people closest to me and how much I was letting them down, and I didn’t want to do that anymore.

“Then, I don’t know, I just tried to just look at my career. I was like, I feel like I’ve got so much left to give to the sport. That’s it. I just trained hard. I just put my head down. Look, let’s get in shape, better shape, first of all. Let’s see, like, how it goes.

“Obviously winning helps. The motivation has been there. It’s easy to train. It’s easier to wake up obviously when things are going great.

“I was just really sick of letting people down. I feel like I’m making people proud now. I feel like there’s not as much negative things being said about me. I just wanted to turn the narrative around almost. That’s basically it. I just was feeling so depressed all the time, so feeling sorry for myself. I just wanted to change that.”

After he reached the final of Wimbledon, Kyrgios was represented by his lawyer in an Australian court. Kyrgios faces a common assault charge relating to an incident in January 2021 in Canberra involving his former girlfriend, Chiara Passari. The case was adjourned to October 4.

He played in doubles in Atlanta, won the men’s singles and doubles title at the Citi Open, reached the quarters in Canada and the round of 32 at Cincinnati. He was maintaining the same form we saw at Wimbledon — since the end of the French Open, he’d won the most matches out of any player on tour.

At Flushing Meadows, Kyrgios’ US Open campaign started with a personally uncomfortable, but professionally dominant win over one of his best pals and doubles partner, Thanasi Kokkinakis. In the second round, against Benjamin Bonzi, he complained to the umpire about the smell of marijuana around the court, and was later fined $7,500 for unsportsmanlike conduct after swearing and spitting in the direction of his box during the match. His third round win was drama-free: a 6-4, 6-2, 6-3 win over J.J. Wolf. But his sternest test to date here this year was against Medvedev.

After the victory, Kyrgios said if Medvedev had won the first set, he knew he’d have lost the match. But Kyrgios took that 63-minute set in a mammoth tiebreak. Medvedev took the second but it was the third and fourth set where Kyrgios said later he felt “so free.” The third set included the bizarre incident in the second game after Medvedev was unable to return a Kyrgios forehand. The ball flew up into the air off Medvedev’s racket, and remained on his side of the court, but before it hit the ground, Kyrgios darted around the net and hammered a volley home.

Had he left it alone, the point would have gone to Kyrgios, but instead his action saw Medvedev awarded it. Kyrgios later called it a “boneheaded play” in his on-court interview. “I thought it was legal,” Kyrgios said. “That’s going to be everywhere on SportsCenter, so I’m going to [look] like an idiot.”

But as he slammed down an ace on match point, it was Kyrgios standing tall on Arthur Ashe. “I didn’t over-celebrate,” he said. “It’s only the fourth round. I got quarterfinals. It was an amazing experience obviously taking down the No. 1 player in the world on Arthur Ashe Stadium. But I don’t really like to celebrate too much after that because I know that if I played him nine more times, he’s probably getting on top of me the majority of the time.”

Up next is big server Karen Khachanov in the quarterfinal. If he wins that, Kyrgios will take another step forward towards his maiden Grand Slam. He said after the Wimbledon final loss that if he’d won that game against Djokovic, then he wasn’t sure if he’d be able to find the motivation to go again. But here in New York, he’s loving the sport again and it’s all coming together.

“It’s the last biggest tournament of the year,” Kyrgios said. “We do realize it’s next week we’re going home. But three more matches potentially, then we never have to play tennis again.”