Britain's Cameron Norrie fought back from two sets down to earn a memorable win over Argentine ninth seed Diego Schwartzman on day one of the US Open.
Norrie, ranked 76th, looked set for a routine defeat before turning it around to win 3-6 4-6 6-2 6-1 7-5 in New York.
Both struggled to hold serve in a match with 58 break points, Norrie saving two match points in the decider before winning in almost four hours.
Kyle Edmund beat Kazakhstan's Alexander Bublik and plays Novak Djokovic next.
The British number two won 2-6 7-5 7-5 6-0 against the unpredictable Bublik, who initially upset the Yorkshireman's rhythm before losing focus and allowing Edmund to take control.
Edmund, 25, faces a tough task to reach the third round of a Grand Slam for the first time in seven attempts, however, with 17-time Grand Slam champion Djokovic lying in wait in round two.
Serbia's world number one Djokovic, who has won all 24 of his matches in 2020, brushed aside Damir Dzumhur of Bosnia-Herzegovina in his opener.
"It was a nice win in terms of the mentality. I play well when I'm expressing myself and explosive, when I start matches not in the right way I have to force that out of me," said Edmund, who is ranked 44th.
"It was a good match to win, I could have fallen off and gone down two sets to love or two sets to one."
The four other Britons in the singles - Andy Murray, Dan Evans, Johanna Konta and Heather Watson - play on Tuesday.
The US Open is the first Grand Slam event to be held since the coronavirus pandemic and is being played behind closed doors at Flushing Meadows.
A host of star names - including defending champions Rafael Nadal and Bianca Andreescu - have withdrawn because of health and travel fears, while Swiss great Roger Federer is missing because of a knee injury.
'I was lucky to get through' - Norrie
British number three Norrie was handed a tough draw by starting against a consistent and competitive player who is a two-time quarter-finalist at the US Open.
The 25-year-old Briton struggled with his timing in the first two sets, hitting 34 unforced errors to leave himself with an uphill battle to reach the second round.
But he cut the mistakes to just five in the third set and, combined with Schwartzman becoming frustrated after receiving a time violation, threatened a comeback.
"The first two sets I was rushing everything and going for too much. I didn't feel myself out there," Norrie said.
"I felt he had done almost nothing to be two-sets-to-love up. I wanted to hit the ball down the middle, get some rhythm and then I kept the momentum going."
Schwartzman struggled to get out of his rut in the fourth, two breaks of serve by the Briton taking the match into a decider, where the break points continued to flow.
Although world number 13 Schwartzman looked to be waning physically, he had chances at 5-3 and 5-4 to clinch victory before Norrie fought back again.
Norrie's reward is another match against an Argentine opponent in the shape of 103rd-ranked Federico Coria.
"The tennis and the level wasn't that great but I had a good attitude throughout and I was happy with that," Norrie added.
"I'm lucky to get through that one. It was a tough one."
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