Dominic Thiem's victory marks the first time in US Open history that a player came back from two sets down to win the title. The Austrian beat Germany's Zverev 2-6, 4-6, 6-4, 6-3, 7-6 (8/6) in 4 hours and 2 minutes.
Second seed Dominic Thiem on Sunday produced a historic comeback to beat Alexander Zverev in five sets and clinch a maiden grand slam title at the Arthur Ashe Stadium.
He is the first Austrian to be crowned singles champion at the US open and the first since Pancho Gonzales in 1949 to fight back from a two-sets-to-love deficit in a final in New York.
The 27-year-old world number three, who trailed 2-6, 1-5 to Germany's Zverev and was down a break early in the third set, limped his way back from 3-5 down in the deciding set on the way to a four-hour comeback to end a three-match losing streak in grand slam finals.
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The climax, which ended in a tie-breaker, saw Thiem squander two match points from 6-4 but Zverev fired his shot wide at the third opportunity.
"Obviously, I want to congratulate Dominic on the first of many Grand Slam titles," said Zverev, who burst into tears during his runner-up speech.
"It was a tough battle. I wish you would have missed a little bit more so I could have held that trophy up," he added.
"I wish we could have two winners today. I think we both deserved it," said Thiem after winning the match.
Thiem's victory meant that men's tennis saw a new grand slam winner after 2014.
The match was watched by just a few dozen people, mostly officials, journalists and event staff, due to the coronavirus restrictions.
shs/sri (AFP, AP, Reuters, dpa)