Roger Federer was on a roll: a new service return, renewed confidence and 28 straight sets won coming into the United States Open final.

Once again, Novak Djokovic was the antidote.

After stopping Federer’s momentum in four sets in this year’s Wimbledon final, Djokovic did the same on Sunday, prevailing against an inspired opponent and a hostile crowd at Arthur Ashe Stadium to underscore his status as the world’s No. 1 player.

Djokovic’s 6-4, 5-7, 6-4, 6-4 victory gave him a second U.S. Open singles title and a 10th Grand Slam singles title, moving him into a tie with Bill Tilden for seventh place on the career list.

Federer remains on top of that pecking order with 17, but Djokovic has prevented him from adding to his record total.

Federer is playing remarkable tennis at age 34, but Djokovic, at 28, is in his prime and remains one of the great tennis conundrums for any opponent with his tactical versatility and peerless defensive skills.

“You have to find the right dose of risk,” Federer said after his latest defeat. “Sometimes I did it well and other times not as well.”

Federer has fared much better against Djokovic than most, and their rivalry is the best the men’s game has to offer at the moment, with Rafael Nadal in a slump that could turn out to be a decline.

Federer and Djokovic have played 42 times, and Djokovic’s victory on Sunday tied the series, 21-21.

It remains a contrast in styles, even more so now that Federer has recommitted to the attack under his co-coach Stefan Edberg, the former Wimbledon and U.S. Open champion who was a net-rushing marvel at his peak. But Federer has yet to win a major title with Edberg in his camp and is now 6-8 against Djokovic in Grand Slam matches.

“In Grand Slams, the conditions are not as fast,” Federer said. “Take tonight. These were the coolest conditions I’ve had for a month. I’m not saying I lost because of that, but it’s a fact. Also, to play aggressively against him for a longer period of time is even more complicated. That was not really the case today. I had the keys in my hand and did some good things, but I just didn’t win the important points to turn the match or get ahead. He was always in front, more or less, and at one moment or another, that pays off. He’s more relaxed than when playing from behind.”

Djokovic is hardly just a defender. He takes plenty of risks of his own and is particularly adept at transforming seeming vulnerability into offense when extended into the corners of the court.

The level of risk required to break him down is enormous, and he is also a moving target. The tactic that works in the first set may not work in the fourth.

“He’s like a shark,” Goran Ivanisevic, the former Wimbledon champion now coaching Marin Cilic, told BBC Radio here. “If he smells blood, he attacks.”

Hardcourts have traditionally been Djokovic’s happiest hunting ground, suiting his precise footwork best. But U.S. Open finals have been more stumbling blocks than showcases for him. He had lost four of the five in which he had played until Sunday. And he literally stumbled in the first set of this final when he lost his balance while changing direction in the fourth game and fell hard to the blue court, scraping his right forearm and looking a bit dazed for the next few points as Federer, who had been broken in the third game, succeeded in breaking back.

“There was still a little bit of moisture on the court, I think, from the rain and a bit of humidity and so forth,” Djokovic said. “I needed two, three games, really, to kind of regroup.”

This much-anticipated final between the world’s No. 1 and No. 2 players was delayed more than three hours by rain. When it finally did begin, it quickly became apparent (and audible) that Djokovic would be playing on the road, with the sellout crowd at Ashe Stadium giving Federer nothing but positive reinforcement and greeting Djokovic’s winners with polite applause at best and frequently cheering for his unforced errors and missed first serves.

Eva Asderaki-Moore, the first female chair umpire to work a U.S. Open men’s singles final, did her best to manage the partisan vibe. Her plea of “Please” became something approximating a mantra, and she also had a remarkable night reading the flow of play, making correct overrules and keeping a firm rein on a match that could easily have escaped control.

A lesser champion than Djokovic might have cracked in such an atmosphere, but this was hardly his first experience with Federer fever, hardly his first experience battling the crowd as well as the opponent.

He has played and won Davis Cup matches for Serbia for many years. He has beaten Lleyton Hewitt of Australia at the Australian Open, Jo-Wilfried Tsonga of France at the French Open and faced Andy Murray of Britain at Wimbledon, although he was the victim when Murray ended a 77-year singles drought for British men at the All England Club in 2013.

At this stage of his remarkable career, Federer plays in front of a home crowd in nearly every venue. For Federer, such support has certainly made it easier for him to continue to find the motivation after having won all the major titles (except the Olympic gold medal in singles) that there are to win.

“It’s definitely one of the reasons I keep playing,” Federer said. “These goose bump moments.”

Djokovic was diplomatic enough to avoid any triumphant notes in his remarks during the awards ceremonies. If he is weary of playing against the Federer bandwagon, he did not mention it.

“I can’t sit here and criticize the crowd — on the contrary, I think it’s logical to expect that a great player and a champion like Roger has the majority of the support anywhere I play him,” Djokovic said in his postmatch news conference. “I accept the fact. Everybody has a choice to support a player that they want to support. And he absolutely deserves to have the support he does because of all the years and success that he has had and the way he carries himself on and off the court. Me, I’m there to earn the support, and hopefully in the future I can be in that position.”

Still, it seemed an appropriate choice that Djokovic chose to watch the movie “300” on the eve of the Open final. Like the Spartan warriors against the Persians, he was outnumbered, too. One of the film’s stars, Gerard Butler, was in Djokovic’s box on Sunday.

“When I looked at him, I said, This is Sparta,” Djokovic said. “It felt great.”

Djokovic has become as tough to break down mentally as he is tough to break down in a baseline rally. And with Federer’s first-serve percentage stuck below 50 percent, Djokovic won the opening set.

Federer found his form in the second, but as at Wimbledon, he was unable to sustain that drive, even with the crowd fully behind him, cheering for Djokovic’s missed first serves and other errors.

Federer’s final chance to extend the match came in the fourth set, when he cut Djokovic’s two-break advantage to 5-4 from 5-2 and then had three break-point opportunities on the Serb’s serve to get back to 5-5.

But Djokovic saved them all and was soon celebrating in the players’ box with his friends, family, and team, which includes Edberg’s longtime rival Boris Becker, now Djokovic’s head coach. Their cheers had been drowned out for most of the night, but they ended up cheering the loudest as Federer, who converted just 4 of 23 break points in the match, sat glumly in his chair.

“I think it was the right game plan, just execution was sometimes missing in some crucial moments,” Federer said. “But other than that, I think I played a good match. Maybe I haven’t played this offensive for a very long time, and that’s maybe the reason as well why maybe I was slightly shaky when it came to the crunch on the break points. Who knows?”

What is clear is that Djokovic’s victory made his season one of the finest in tennis history — even better in Grand Slam terms than his remarkable 2011 season, when he won three of the major singles titles and lost in the semifinals of the French Open to Federer.

This year, he joined Federer and Rod Laver as the only men in the Open era to reach all four major finals, his only defeat coming in the final of the French Open against Stan Wawrinka, Federer’s inspired Swiss compatriot.

Federer was clearly inspired himself on this summer hardcourt swing: winning in Mason, Ohio (beating Djokovic in the final), and then reaching the U.S. Open final without losing so much as a set. But beating Djokovic over a best-of-five-set match is still the biggest challenge in men’s tennis, and Federer, for all his tennis genius, has not managed it since the Wimbledon semifinals in 2012.

At least he knows his efforts are appreciated.

“It’s a great consolation for me to receive this kind of support in a country that is a long way from Switzerland and is one of the countries that is the most powerful in sports in general,” Federer said of Sunday’s crowd. “They love winners here.”

Djokovic might disagree.