NEW YORK -- Novak Djokovic limited big-serving Ben Shelton to five aces and broke him five times. He pushed back when the 20-year-old unseeded American produced a late stand that got the home crowd into the match.

And after finishing off a 6-3, 6-2, 7-6 (4) victory to reach his record-tying 10th US Open final, Djokovic added a touch of insult by mimicking the Shelton's "Hang up the phone!" celebration gesture.

Djokovic then pointed to his temple and pounded his fist on his chest, before a stone-faced Shelton met him at the net for the most perfunctory of handshakes. A year after Djokovic could not travel to the United States for the Open because he is not vaccinated against COVID-19, the 36-year-old from Serbia is one victory away from a fourth title at Flushing Meadows and 24th Grand Slam championship overall.

"These are the kind of matches and occasions that I still thrive on. They still get me going and inspire me to wake up and work hard like the young guys," said Djokovic, who would be the oldest man to win the US Open in the professional era, which began in 1968.

"I still feel I have something in my legs left," he said. "I still feel I have something to give to the sport."

Shelton, who entered the day with a tournament-high 76 aces, made things interesting in the third set, lifting his level of play as Djokovic seemed to get a bit tight when the finish line neared. Shelton broke for the only two times in the match, even held a set point at 5-4 and later erased a match point on the way to forcing the concluding tiebreaker.

But Djokovic, always so tough when the going gets tough, pulled out the win.

"Got to hold the nerves and try to be composed in the moments that matter," he said. "Things were going smoothly for me ... and then it was anybody's game at the end of the third set."

On Sunday, he will face either defending champion Carlos Alcaraz -- who defeated Djokovic for the Wimbledon title in July -- or 2021 US Open champ Daniil Medvedev.

"Of course, I expect the toughest match of the tournament for me," said Djokovic, who fell one win shy of a calendar-year Grand Slam when Medvedev beat him in the final two years ago, "regardless of who's going to be across the net."

If Djokovic leaves with the hardware this time, he would break a tie with Serena Williams for the most major singles championships in the Open era and match Margaret Court's all-time singles record.

No matter who the opponent or what the outcome is in the final, No. 2 seed Djokovic will replace No. 1 Alcaraz atop the ATP rankings on Monday.

Djokovic's 10th US Open final appearance ties Bill Tilden for the most by a man in tournament history. For the third time in his career, Djokovic has reached all four major finals in a calendar year. He won the Australian Open and French Open before Alcaraz denied his quest for the calendar Grand Slam.

Djokovic vs. Shelton certainly seemed like a mismatch beforehand: Djokovic was participating in his record 47th Slam semifinal and his 100th US Open match; the 47th-ranked Shelton, who just last year was busy winning an NCAA singles title for the University of Florida, was in his first major semi and only his seventh career match at the Open.

And it quickly looked like a mismatch, too, once the semifinal began in Arthur Ashe Stadium, where there were additional police officers and security guards a day after four climate protesters -- including one man who glued his bare feet to the concrete on the ground in the stands -- caused a 50-minute delay during Coco Gauff's victory that put her in the final.

The retractable roof was closed Friday because of rain in the forecast, creating an echo for all of the yells and applause that served as a soundtrack for the players' entrances.

Shelton was greeted warmly when he walked out with white headphones over the black hood of his sweatshirt and flashed a peace sign. Djokovic followed with a wave to acknowledge the crowd, and the roar he received was just as loud and enthusiastic. Maybe more so.

In his sleeveless muscle shirt, Shelton came out smacking his high-rate lefty serves, reaching 136 mph and 138 mph in the opening game. Later, he'd crank it up to 140 mph and stand there shaking his racket or emphasize an ace at 145 mph with a scream.

"These are the kind of matches and occasions that I still thrive on. They still get me going and inspire me to wake up and work hard like the young guys. I still feel I have something in my legs left. I still feel I have something to give to the sport."

Novak Djokovic

It was as though Djokovic said with his play: "Go ahead and enjoy those jaw-droppers; I'll just be over here with my modest 122 mph serves and beat you by getting the better of things once the ball is in action."

A couple of brief lapses by Shelton, ever-so-slight lulls against the relentlessly intense Djokovic, were enough to shift things early. A poor drop shot into the net here, a flubbed volley there, and Shelton got broken to trail 4-2. Djokovic did not celebrate wildly. Or at all, truly.

He simply strode calmly to a towel box in a corner to wipe off. Made sense: It was just 20 minutes and six games in. Technically, nothing had been settled.

But the ultimate outcome never appeared in any doubt. Well, OK, there was that little burst of excellence from Shelton after he trailed 4-2 in the last set.

In the end, though, all of Djokovic's experience prevailed, along with that ability to grind away, point after point, with his sneaker-squeaking, body-bending defense and more.

ESPN Stats & Information and The Associated Press contributed to this report.