NEW YORK — World No. 1 Jannik Sinner arrived in New York more than two weeks ago facing a slew of questions and scrutiny over the news that he had been exonerated and avoided suspension after twice testing positive for a banned substance in March.

His expectations for the US Open were “low,” he said at the start.

But he leaves as a champion, having left little doubt about his status as the best hard-court player in 2024.

Sinner, a 23-year-old from Italy, won the US Open on Sunday behind a dominant 6-3, 6-4, 7-5 effort against American Taylor Fritz in front of a lively, celebrity-filled Arthur Ashe Stadium crowd that was largely against him. There were “U-S-A” chants and “Let’s go, Taylor” cheers throughout, but Sinner was unfazed. He didn’t drop a single point on his first serve over the final two sets of the match.

“He was too good,” the No. 12-seeded Fritz said during the on-court trophy presentation. He later called Sinner “the best player in the world right now.”

Having collected his first major title at the Australian Open in January, Sinner became the third man — and first since Guillermo Vilas in 1977 — to win his first two Grand Slam trophies in the same season. He’s also the second Italian player to win a singles title at the US Open, joining 2015 women’s champion Flavia Pennetta.

For Sinner, the victory marked an emotional end to a challenging few months. The world found out on Aug. 20 that he tested positive for a trace amount of clostebol, a banned anabolic steroid, twice in an eight-day span during the Indian Wells tournament, but was cleared because his use was ruled unintentional — his defense was that the steroid entered his system via a massage from a team member he later fired.

“[It] was difficult because the pre-tournament circumstances weren’t easy,” Sinner said Sunday. “I felt that I have grown match by match and that my confidence level went higher and higher … I’m happy how I handled this one. I’m just excited to have this trophy with me.”

Sinner has faced questions throughout the tournament about the doping case and what followed. Several players questioned the fairness of the ruling and pondered whether he had received special treatment due to his No. 1 ranking.

Sinner, for his part, called the situation a “mistake” and was adamant about his innocence and that he went through the “same process” as everyone else.

Despite the news, Sinner was for the most part warmly received by the New York crowd throughout his run. Even during the final, dozens of Italian flags were spotted in the crowd, and his highlight-worthy points were met with loud ovations.

After struggling in the opening set of his first match against American Mackenzie McDonald, Sinner showed little weakness the rest of the way. He dropped just one more set — against 2021 US Open champion Daniil Medvedev in the quarterfinals — en route to the title.

Fritz, a 26-year-old Californian who was playing in his first major final, opened with an early 3-2 lead, but Sinner responded by winning the next four games to take the set and control of the match.

In the third set, with the score tied at 3-all, Fritz showed signs of life with an overhead winner in the seventh game for a 15-30 lead on Sinner’s serve. He yelled “Let’s go!” to the delight of the crowd, most of whom rose to their feet in appreciation. Fritz ultimately secured the break and took the next game on his serve for a 5-3 lead.

But he couldn’t close out the set. Sinner almost clinically rattled off the next four games — each point increasingly silencing the crowd — to secure the win.

When it was over, Sinner raised his arms above his head and closed his eyes as he tilted his head back. Those in his player box jumped to their feet while Darren Cahill, one of his coaches, slumped over in his seat and wiped away tears.

“This title, for me, means so much,” Sinner told the crowd as he collected the trophy from Andre Agassi, “because the last period of my career was really not easy.”

“I feel like the fans obviously, American fans, been wanting a men’s champion for a long time, and … I’m pretty upset with how I played. I feel like, I don’t know, I feel like I almost let a lot of people down.”

Taylor Fritz

Sinner, during his postmatch news conference, credited his team and family for keeping him focused despite everything going on off the court.

“What allowed me to do that was always the people who are close to me daily, people who know me already from when I was very young, and also my family and my team and everyone who supports me daily,” Sinner said. “I always try to stick together with them, especially when the moments are getting difficult and tough, because I know that they can help me in these moments.”

Sinner is the fourth different man to win both the Australian Open and US Open in the same year since 1988, when the Australian major transitioned from grass to hard court. With Aryna Sabalenka having swept both the Australian Open and US Open, too, it’s the first time that the same man and the same woman won both hard-court majors in the same year since 1988 (Mats Wilander and Steffi Graf did so that year).

It also marked a turning point in the men’s game as Sinner and Carlos Alcaraz, 21, combined to win all four of the year’s major titles. It’s the first season since 2002 that no member of the “Big Three” — Novak Djokovic, Rafael Nadal and Roger Federer — won a Slam.

Sunday was a devastating result for Fritz, who had been looking to snap a 21-year major singles title drought by American men. Andy Roddick’s win at the 2003 US Open was the last time an American man won a Grand Slam, and Fritz was the first American man to reach a major final since Roddick finished as the runner-up at Wimbledon in 2009.

“There’s obviously a lot of positives, and when I get some time to cool down then I’ll be happy about the fact that I made it to the finals,” Fritz said. “But right now I’m pretty disappointed in just a lot of things on the court, how I played, how I hit certain shots. It sucks.

“And I’m not saying that it necessarily would have made a difference. I don’t know if it would have, but I just would have liked to have played better and given myself a better chance. It’s really disappointing right now. … I feel like the fans obviously, American fans, been wanting a men’s champion for a long time, and … I’m pretty upset with how I played. I feel like, I don’t know, I feel like I almost let a lot of people down.”

Despite the heartbreak of the final, Fritz is still having a breakthrough year. He became the first American man to reach three major quarterfinals in a season since Roddick (2007) and the first to make the second week in all four Slam events since Agassi in 2003.

With his run to the championship match, Fritz will now move back into the top 10 in the rankings at No. 7.

Sinner now has a 4,105-point lead over new No. 2 Alexander Zverev. Djokovic, the 2023 champion at Flushing Meadows who was upset in the third round, falls to No. 4 behind Alcaraz.

ESPN Research and The Associated Press contributed to this report.