Nick Kyrgios stood amazed, his mouth agape and his eyes popped wide over a shot his opponent had just made in the third set of their third-round match on Saturday (US time).

Kyrgios had scooped a drop shot at a seemingly safe angle, but Roger Federer sprinted a few feet wide of the doubles alley, reached down with the head of his racquet about 2 inches off the surface of the court, and tapped a forehand around the net post.

The ball lifted less than a foot into the air and bounced past Kyrgios, a winner for Federer. The moment of brilliance, one of the many dazzling shots that Federer has produced at various points in his illustrious career, caused a sustained roar from the crowd at Arthur Ashe Stadium on Saturday afternoon.

But perhaps no one appreciated the shot more than its victim.

“If anyone else is doing those shots against me, I’m probably not too happy,” Kyrgios said. “But it’s Roger. I was pretty happy.”

What the… What???!! #AroundTheNet#USOpen #USOpen2018 #USOpen18 #USOpenTennis #ArthurAsheStadium #Federer #Kyrgios #FedererVsKyrgios #FedererKyrgios pic.twitter.com/3wT80NCHNR

— Alex Malaos (@AlexMalaos) September 2, 2018

Kyrgios, a 23-year-old Australian, is an immensely talented and often inscrutable player who has been criticised for boorish behaviour and a periodic lack of interest on the tennis court. He even received unwanted attention for being the focus of an encouraging speech from a chair umpire during his second-round match at the US Open on Thursday.

Here was something else: Kyrgios was actually happy to see his opponent score a significant point against him in a match Federer would go on to win, 6-4 6-1 7-5 to reach the fourth round.

“It was almost unreal,” Kyrgios said. “Almost got to the point where I wanted him to start making shots like that.”

For a moment, after the ball slid past him, Kyrgios transformed into a star-struck tennis fan, even waving briefly to get Federer to look at him so he could demonstrate his appreciation directly to the great champion.

Federer had already begun walking back to the baseline to receive the next serve. So Kyrgios gently bounced a ball off his racquet toward Federer, who glanced back and smiled. He, too, had to appreciate the sheer genius he had just displayed.

Federer later said he counted the shot as one of the best of his career, citing three others that he would place on such a list. There was an overhead slam against Andy Roddick in Basel, Switzerland, in 2002, a flicked shot over Andre Agassi in Dubai in 2005, and a between-the-legs winner against Novak Djokovic at the 2009 US Open.

https://www.youtube.com/watch?v=jMs7ebIyz38

Saturday’s highlights-reel shot, he noted, is possible only in a large stadium with the net posts in the doubles alley and plenty of space to the side of the court.

“You don’t get an opportunity to hit around the net post very often, because in practice, I mean, you can’t really train them,” he said.

“The net is out further and the court is more narrow, so for a shot like this to happen in a practice, you will be running into a fence. And you will hit it into the net.”

Kyrgios, the No.30 seed, recovered to win that game, and ultimately it was a 3-3 game in the first set that proved to be the difference. Federer was having difficulty catching up to Kyrgios’ thunderous serve, which was clocked at 136mph multiple times, and he fell behind on his own serve, 0-40.

But he eventually won the 18-point game, saving four break points in all, and after that, Kyrgios’s intensity level seemed to drop.

Kyrgios reacts to Federer’s winner that went around the net post in the third set. Photo: AAP

“I know if I can somehow dig myself out of that game, I don’t know how I got into the love-40 game position. It’s just huge to try to get out of it somehow,” said Federer, the No.2 seed and a five-time US Open champion. “Doesn’t have to be pretty. Doesn’t have to be crazy shotmaking. Just you have to get back to deuce somehow and maybe you can breathe a bit.”

At the end of the first set, which Federer won with a backhand return down the line, Kyrgios returned to his chair and yelled at the people sitting in his box for what he felt was vague and unhelpful advice — like telling him to get his first serve in. For most of the second set, Kyrgios was muttering to himself and shaking his head in between points.

In the fourth round on Monday, Federer will play another Australian, John Millman, ranked 55th. Millman, 29, defeated Mikhail Kukushkin of Kazakhstan, 6-4 4-6 6-1 6-3 to advance to the round of 16 at a major for the first time. Federer played Millman once before, three years ago in Brisbane, Australia. Federer lost the first set but won the next two.

Joao Sousa of Portugal also reached the fourth round of a major for the first time, upsetting 17th-seeded Lucas Pouille of France, 7-6 (7-5) 4-6 7-6 (7-4) 7-6 (7-5).

Fourth-seeded Alexander Zverev also lost, 6-7 (7-1) 6-4 6-1 6-3 to his German countryman Philipp Kohlschreiber. He will play No.21 seed Kei Nishikori of Japan, who beat No.13 Diego Schwartzman of Argentina, 6-4 6-4 5-7 6-1.

No.10 David Goffin advanced with a 6-4 6-1 7-6 (7-4) win over Jan-Lennard Struff and will play No.7 Marin Cilic.

–The New York Times