Alexander Zverev has won his second grand slam title, lifting the US Open trophy after being completely oblivious on match point of his 6-3 7-6 (7-2) 5-7 6-2 win over home hero Ben Shelton in New York.

The crowd rose as one after Zverev held serve in the eighth game of the fourth set but the 29-year-old was unaware he had been on the brink of a $US5.5 million ($A7.7m) victory.

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He thought the score had moved to 5-1 until brother and former world No.25 Mischa, helpfully seated on the court in the new coaching boxes, delivered the news that it was all over.

Jelena Dokic said Zverev was simply so “locked in” he never realised it was championship point — perhaps in a positive for handling any nerves.

“That will go down as one of the great reactions of a grand slam champion,” Todd Woodbridge added on Nine.

Zverev finally broke through in the majors by winning this year’s French Open and followed up by finally adding the title in New York that he so painfully let slip away in 2020.

He thought this title would come then and still acknowledges it should have, having won the first two sets against Dominic Thiem and being within two points of victory before becoming the first man to blow a two-set lead and lose in the final since 1949.

Whatever ghosts were left from then are long gone now.

The No.1 seed in a Grand Slam for the first time, Zverev capitalised on Shelton’s shaky start in his first major final, played a nearly flawless tiebreaker on serve and then turned back Shelton’s comeback attempt in front of a crowd that desperately cheered him on.

Shelton was trying to win the first title by an American man since Andy Roddick won in Flushing Meadows in 2003, as well as the first by a Black man since Arthur Ashe in 1968.

Zverev encouraged Shelton, 23, during their post-match embrace in declaring he is sure to win a grand slam in the future.

“I know that today 99.9 per cent of the people wanted Ben to win so I’m very sorry first of all,” Zverev later told the crowd.

“But second it was an incredible atmosphere to play in even though I know that the crowd was against me, the crowd was always incredibly fair. We as players appreciate it, you guys brought the noise and energy. Thank you for that.”

Zverev paid tribute to his mother for never putting a limit on what he could achieve despite being diagnosed with Type 1 diabetes at just four years old.

“I want to thank one more person who is never actually watching my matches but is the most important person in my tennis life and in my life in general,” he said.

“Because when your four-year-old son gets diagnosed with diabetes and doctors in the office tell you that life and sports will be very, very limited for that child it takes a very, very strong mother to walk out of those offices and say ‘my son will be whatever he wants to be, if he wants to be a tennis player he will be a tennis player, if he wants to do something else he will do something else. But this illness will not define us’.”

The German also noticed Shelton’s partner and US soccer star Trinity Rodman was in the stands after she had rushed from her NWSL game earlier in the day.

“I thought you had a game today, no? Well done to you as well. You’re the lucky charm. Not today, but usually,” he said.