Top-seeded Jannik Sinner surprisingly dropped his first set of the U.S. Open before rallying for a 2-6, 6-2, 6-1, 6-2 win over Mackenzie McDonald in the first round Tuesday in New York.

McDonald, an American ranked No. 140 in the world, had the home crowd on his side as he broke the Italian's serve in an opening game that featured five break points. Sinner came back to tie it 2-2 before McDonald rattled off the final four games of the set.

McDonald broke the World No. 1 again in the first game of the second set, but Sinner responded by winning four in a row and took control for the rest of the match.

"I started not in the best way, for sure, but the first match in every tournament is not easy," Sinner said in his on-court interview. "You have to accept it. He played really, really well at the beginning and I tried to stay there mentally, tried to get into a rhythm. I did that at some point in the second set and then just tried to keep going, so I'm very happy to be in the next round."

Sinner, who won the Australian Open in January for his first major trophy, is playing his first tournament since news broke that he tested positive for a banned steroid twice in March but avoided suspension.

Sinner hit 12 aces to McDonald's two, saved 7 of 11 break points and capitalized on his opponent's 46 unforced errors. This marked Sinner's first win inside Arthur Ashe Stadium.

"We go day by day. (Wednesday) I have a day off and we will try to get a little bit more rhythm and try to improve for the next match," Sinner said.

He'll face an American for the second straight round -- 20-year-old Alex Michelsen, who defeated countryman Eliot Spizzirri 6-1, 7-5, 6-3.

Tuesday will be remembered for the longest match in U.S. Open history. After three tiebreakers in the first three sets, Great Britain's Daniel Evans outlasted Russian 23rd season Karen Khachanov 6-7 (6), 7-6 (2), 7-6 (4), 4-6, 6-4 in five hours, 35 minutes.

Evans trailed 4-0 in the final set before reeling off six games in a row.

Third-seeded Carlos Alcaraz began his pursuit of a third consecutive Grand Slam title with a four-set win. The Spaniard downed Australian qualifier Li Tu 6-2, 4-6, 6-3, 6-1. Alcaraz won 80 percent of his first-serve points and finished with a 50-19 edge in winners.

No. 5 seed Daniil Medvedev, like Sinner, needed four sets to get out of the first round. He defeated Dusan Lajovic of Serbia 6-3, 3-6, 6-3, 6-1.

"Second set, (Dusan) played an amazing level. I don't think you can play better than he did," Medvedev said. "I was really tired at the end of the second set. And then I managed to put some extra pressure on him a little bit. I played aggressive, didn't face a break point afterwards."

Polish No. 7 seed Hubert Hurkacz opened his tournament with a 6-3, 7-6 (4), 7-6 (3) win over Kazakh qualifier Timofey Skatov. No. 10 seed Alex de Minaur of Australia prevailed 6-3, 6-4, 5-7, 6-4 over Marcos Giron. Hurkacz and de Minaur avoided the carnage that befell several other seeded players in first-round action.

No. 11 seed Stefanos Tsitsipas of Greece is already out, as Australia's Thanasi Kokkinakis beat him 7-6 (5), 4-6, 6-3, 7-5.

"That was incredible. ... I expected a war," Kokkinakis said. "It was physical out there. I have a tendency to drag these matches on into real long battles. I just tried to stay focused on every point."

No. 14 Tommy Paul of the United States won the last match of the night, topping Italy's Lorenzo Sonego 6-4, 6-2, 5-7, 6-2.

Also, Jakub Mensik of the Czech Republic swept past No. 19 Felix Auger-Aliassime of Canada 6-2, 6-4, 6-2; Belgium's David Goffin beat No. 22 Alejandro Tabilo of Chile 7-6 (7), 6-1, 7-5; and Australia's Christopher O'Connell eliminated No. 26 Nicolas Jarry of Chile.

British 25th seed Jack Draper led 6-3, 6-0, 4-0 when Chinese opponent Zhizhen Zhang retired. No. 16 seed Sebastian Korda, No. 24 Arthur Fils of France, No. 30 Matteo Arnaldi of Italy and No. 31 Flavio Cobolli of Italy also advanced.

Other winners Tuesday were Australians Tristan Schoolkate, Jordan Thompson and Max Purcell; Argentina's Facundo Diaz Acosta and Mariano Navone; Nuno Borges of Portugal; Tomas Machac of the Czech Republic; Frenchman Adrian Mannarino; Russia's Roman Safiullin; Finland's Otto Virtanen; Botic van de Zandschulp of the Netherlands; Hungary's Fabian Marozsan; Canada's Gabriel Diallo; Italy's Mattia Bellucci and Belgium's Zizou Bergs.

--Field Level Media