World No.1 Jannik Sinner has beaten Taylor Fritz 6-3 6-4 7-5 with a relentless baseline game to win the US Open men’s singles championship, less than three weeks after being exonerated in a doping case.

Sinner held his arms aloft in celebration after breaking Fritz to clinch the title and cheers rang around Arthur Ashe Stadium on Sunday (local time), even though home fans had hoped to see Fritz end a 21-year American drought in men’s grand slams.

The 23-year-old Italian was under a cloud of controversy at the start of the tournament after revelations that he tested positive twice for an anabolic agent in March.

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He avoided a ban when an independent tribunal accepted his claim that the positive tests were the result of an unintentional contamination.

The top seed blocked out the furore in New York and with the win claimed his second grand slam title after winning the Australian Open in January.

Briefly describing the controversy as “not easy” to have dealt with this year, Sinner says he has already been reminded to enjoy his life away from tennis.

“I would like to dedicate this title to my aunt, because she is really not feeling well health-wise,” he said.

“I don’t know how much I’ll still have her in my life. It’s so nice that I can share positive moments still with her, she was a very important person for my life and she still is.

“If there would be the biggest wish I would wish everyone the best health to everyone but unfortunately it’s not possible.”

He is the first man since Guillermo Vilas in 1977 to win his first two grand slam trophies in the same season, something such greats as Novak Djokovic, Rafael Nadal and Federer never accomplished.

Fritz got off to a dreadful start when he handed Sinner a break of serve with an unforced error in the first game. He settled his nerves, breaking back in the fourth game and surviving a 23-shot rally to save break point in the fifth.

But it was only a matter of time before Sinner would hit his stride and he broke the 12th-seeded American with a perfectly placed drop shot in the seventh game. Fritz dropped his serve again on set point.

The fired-up home crowd tried to lift Fritz with chants of “USA!” in the second set.

However, the momentum swung in Sinner’s direction as he broke Fritz on set point from the baseline, and he piled further misery on the American when he clawed back from triple break point down in the opening game of the third set.

Fritz clung on and even went up a break but was left smacking his racquet on to the court in frustration when he hit a volley into the net to let Sinner break back in the 10th.

Sinner broke for a sixth time in the contest to wrap up the win, with Fritz swiping a forehand into the net on match point.

With US great Andre Agassi on court for the presentation ceremony, Fritz told the crowd: “I know we’ve been waiting for a champion for a long time so I’m sorry I couldn’t get it done this time. But I’m gonna keep working and hopefully I’ll get it the next time.”

Andy Roddick’s triumph at Flushing Meadows in 2003 was the last slam title for a man from the United States.

The last before Fritz to even contest a final at one of the four biggest tournaments in tennis also was Roddick, who lost to Roger Federer at Wimbledon in 2009.