NEW YORK >> Halfway through a second set that lasted 1 hour, 44 minutes, a test of tenacity as much as talent amid a U.S. Open final as exhausting as it was exhilarating, Novak Djokovic and Daniil Medvedev engaged each other in a 32-stroke point.

It was among many such elongated exchanges between two men whose styles are nearly mirror images, and Djokovic capitulated on this one by netting a backhand. He fell to his back and stayed down, chest heaving. The crowd roared. Djokovic sat up but remained on the ground for a bit. The crowd roared more, appreciating the effort, saluting the entertainment.

Using every ounce of his energy and some serve-and-volley guile — an old man with new tricks — Djokovic emerged for a 6-3, 7-6 (5), 6-3 victory over Medvedev at Flushing Meadows to claim a historic 24th Grand Slam title on Sunday night in a match more closely contested than the straight-set score indicated.

“I never imagined that I would be here standing with you talking about 24 Slams. I never thought that would be the reality,” said Djokovic, a 36-year-old from Serbia and the tournament’s oldest male champion in the Open era, which dates to 1968. “But the last couple of years, I felt I have a chance, I have a shot for history, and why not grab it if it’s presented?”

He moved one major singles title ahead of Serena Williams to become the first player to win 24 in the Open era. Margaret Court also collected a total of 24, but 13 of those came before professionals were admitted to the Slam events.

“It obviously means the world to me,” said Djokovic, who will return to No. 1 in the rankings on Monday.

There were moments, particularly in the miniseries of a second set, when Djokovic appeared to be faltering. After some of the most grueling points — and there were many — he would lean over with hands on knees or use his racket for support or pause to stretch his legs.

He allowed Medvedev to come within a single point of taking that set while returning at 6-5. Djokovic rushed the net behind his serve, and while Medvedev had an opening for a backhand passing shot, he did not come through.

That was a key adjustment: When Djokovic was looking more bedraggled, he turned to serve-and-volleying, not his usual sort of tactic, to great success. He won 20 of 22 points he played that way, and 37 of 44 overall on the points when he went to the net, some with spectacular volleys or half-volleys at angles a pool shark would appreciate.

Medvedev never countered.

“I should have been less stubborn,” Medvedev said.

This was Medvedev’s fifth Grand Slam final and he is now 1-4, with two losses to Djokovic and two to Rafael Nadal. The one victory? That came against Djokovic in the 2021 final at Flushing Meadows, stopping a bid for the first men’s calendar-year Grand Slam in more than a half-century.

Djokovic’s fourth championship in New York, where he was unable to compete a year ago because he isn’t vaccinated against COVID-19, goes alongside his 10 trophies from the Australian Open, seven from Wimbledon and three from the French Open, extending his lead on the men’s Slam list. Nadal, sidelined since January with a hip problem, is next with 22; Roger Federer, who announced his retirement a year ago, finished with 20.

When it was over, Medvedev tapped Djokovic on the chest as they talked at the net. Djokovic flung his racket away, put his arms up and then knelt on the court, with his head bowed. And then the celebration was on. First he found his daughter for a hug. His son and wife came next, along with his team.

Soon, Djokovic was donning a shirt with “24” and “Mamba Forever” written on it as a tribute to the late NBA star Kobe Bryant, who wore that jersey number. And on top of that went a white jacket with the same significant number stamped on the chest.

“Kobe was a close friend. We chatted a lot about the winner’s mentality when I was struggling with injury and trying to make my comeback, work my way back to the top of the game,” Djokovic said. “He was one of the people that I relied on the most.”

As good as ever, Djokovic went 27-1 in the sport’s most prestigious events this season: The lone blemish was a loss to Carlos Alcaraz in the final at Wimbledon in July. Djokovic will rise to No. 1 in the rankings on Monday, overtaking Alcaraz, who was the defending champion at Flushing Meadows but was eliminated by No. 3 Medvedev in the semifinals.

At the start Sunday, with the Arthur Ashe Stadium retractable roof shut because of rain in the forecast, Djokovic was comfortable as can be. No sign of the occasion weighing on him, no trace of the tension he acknowledged briefly arose late in his semifinal against unseeded American Ben Shelton.

His exemplary movement good as ever, every stroke just so, Djokovic came out as his best self. He grabbed 12 of the first 16 points — three via aces perfectly placed, and with pace, and four via exchanges that lasted 10 strokes or more — along the way to leads of 3-0 and 4-1.

Medvedev, in contrast, seemed tight, jittery, the looping swings of his white racket breaking down repeatedly, whether on a trio of double-faults in the opening set or during the lengthier points.

Beyond that, though, Djokovic was as reliable as a metronome, anticipating nearly everything headed his way and scurrying this way and that to retrieve and respond, as is his wont.

On this afternoon-into-evening, support came from thousands in the stands, not only the folks invoking his two-syllable nickname while chanting, “Let’s go, No-le, let’s go!” or those in his guest box, including Oscar winner Matthew McConaughey, one of many A-listers on hand.

Djokovic relies on analytics and what a foe’s tendencies are. He leans on instinct and a masterful ability to read opposing serves and groundstrokes. On Sunday, his blue shoes carried him right where he needed to be, more often than not, and his flexibility — turning, bending, contorting, stretching, sliding, defending with his back to the net, even — allowed him to keep the ball in play, when required, and create flip-the-switch offense, too, if desired.

Medvedev plays similarly. Points lasted 25 shots, 35 shots, more.

Was Djokovic perfect? No. But, wow, he came close in sections, and he was absolutely good enough throughout to win, as he so often is.

“First of all, Novak, I want to ask: What are you still doing here? Come on,” Medvedev joked during the trophy presentation.