A U.S. Open unlike any other finished unlike any other — with an unprecedented fifth-set tiebreaker as Dominic Thiem became the first man in 71 years to win the final after dropping the opening two sets.

So close to defeat in a nearly empty Arthur Ashe Stadium — fans were banned because of the coronavirus pandemic — Thiem slowly but surely turned things around against a faltering Alexander Zverev and pulled out a 2-6, 4-6, 6-4, 6-3, 7-6 (6) victory at Flushing Meadows for his first Grand Slam title.

The match ended with both men fighting leg cramps and, clearly, nerves.

“Somehow,” said Thiem, a 27-year-old from Austria, “the belief today was stronger than the body, and I’m super happy about that.”

When a backhand from Zverev landed wide on the third championship point, a weary Thiem dropped to his back way behind the baseline and covered his face with his hands. When he arose, he was met by Zverev, who walked around the net to clasp hands, then embrace his friend and foe, two sights rarely seen in this era of social distancing.

Thiem then rested his head on the shoulder of the taller Zverev, who himself came within two points of what would have been his first major triumph.

“I wish we could have two winners today,” Thiem said. “I think we both deserved it.”

He is the first man to win the American Grand Slam tournament after trailing 2-0 in sets in the final since Pancho Gonzalez did it against Ted Schroeder in 1949 at an event then known as the U.S. Championships and held in Forest Hills.

The event never had been settled by a fifth-set tiebreaker; no major tournament ever had until Novak Djokovic edged Roger Federer that way at Wimbledon in 2019.

“I was a few games away, a few points away,” said Zverev, who was trying to give Germany its first male Grand Slam champion since Boris Becker in the 1990s. “I’m 23 years old. I don’t think it’s my last chance.”

Zverev choked up when he mentioned that his parents hadn’t been able to travel to New York because they tested positive for COVID-19, although he said they are now healthy.

As Thiem stepped forward to pose for pictures with his shiny new bit of hardware, Zverev remained a few feet behind, one hand clutching his less-impressive silver tray, the other hand on a hip.

The proceedings took 4 hours, 2 minutes. And to think: After just 1 1/2 hours, Zverev was up by two sets and a break in the third at 2-1.

“The match turned when he broke me for the first time in the third set,” Zverev said. “He started playing much better, and I started playing much worse.”

Zverev, of all people, should have known what might have seemed like an impossible hill to climb for Thiem was, indeed, achievable. After all, in Thursday’s semifinals, it was Zverev who trailed 2-0 in sets against Pablo Carreño Busta before coming back to win.

Thiem began the day 0-3 in Grand Slam finals, but always faced a member of the Big Three of men’s tennis in those others. This time, he was the favorite and came out jittery, but eventually worked his way out of that, while Zverev went from cool and confident to passive and pushed around.

The fifth set was just as back-and-forth as the other four, the mistakes rising with the tension and the history in the offing.

Thiem broke in the opening game when Zverev shanked a pair of forehands. Zverev broke right back — and pierced the silence with a rare cry of “Come on!” — when Thiem double-faulted.

Then it was Zverev’s turn to nose ahead, breaking for a 5-3 lead when Thiem sent a down-the-line backhand wide and leaned over, gasping for air.

But with a chance to serve out the biggest win of his nascent career, Zverev faltered, getting broken right back when he pushed a volley into the net.

That began a three-game run for Thiem, who broke to lead 6-5, earning his own chance to serve for it when Zverev netted a backhand, followed by a long forehand.

After having a trainer check on his right leg during the ensuing changeover, Thiem couldn’t seal the deal, either, and on they went to the tiebreaker. Zverev double-faulted twice and offered up one second serve at 68 mph, about half the speed he’s capable of.

While this was the No. 7-ranked Zverev’s first Slam final, this was the first one the No. 3-ranked Thiem was supposed to win, following losses to 12-time French Open champion Rafael Nadal at Roland Garros in 2018 and 2019, then to eight-time Australian Open champion Djokovic at Melbourne Park this February — back before the pandemic upended the world and put tennis on a five-month hiatus.

Instead of wild applause and loud shouts greeting great exchanges, the soundtrack Sunday mainly came from outside the largest court in tennis, courtesy of roaring airplanes, rumbling trains, revving car engines, honking horns and wailing sirens. There was the occasional polite applause from the dozens of tournament workers allowed in the stands — and, deep into the match, yells from the players’ entourages.

But the louder crowd noise heard by TV viewers was fake, added by the broadcaster.

Unable to draw from support in what’s always been an electric environment, on an evening that felt more like a glorified practice session than a match with so much at stake, both men were sluggish at times, listless, even. The play was hardly perfect: They combined for 120 unforced errors to only 95 winners. In a curious parallel, Zverev balanced his 15 aces with 15 double-faults, and Thiem had eight in each category.

Normally, the U.S. Open closes each Grand Slam season, but what about 2020 has been normal?

Wimbledon was canceled for the first time since World War II, while the French Open was postponed from its originally scheduled May start and now will begin in two weeks.

Another way in which this whole event was different: Federer, Nadal and Djokovic had won the preceding 13 major trophies. But Federer and Nadal didn’t enter the U.S. Open, while Djokovic was defaulted in the fourth round for accidentally hitting a line judge with a ball he smacked in anger after dropping a game.

Thiem — barely, just barely — was the one who took advantage of the chance to sneak into the club of champions.

“Such a big relief. I mean, obviously it was huge pressure in the match, huge emotions,” Thiem said. “It tough to stay there and to still believe. But I did.”