Carlos Alcaraz saw his bid for a third consecutive Grand Slam title end in the second round of the U.S. Open on Thursday, as the third-seeded Spaniard lost 6-1, 7-5, 6-4 to the Netherlands' Botic van de Zandschulp.

It was the earliest exit in a major tournament for Alcaraz, 21, since his first full year on tour in 2021.

The 2022 U.S. Open champion and 2023 Wimbledon champion, Alcaraz added titles at the French Open and Wimbledon this summer.

van de Zandschulp, 28, has never reached the quarterfinals of a Grand Slam event, and he has never won an ATP Tour tournament. He is currently ranked 74th in the world.

"Of course I had some nerves," van de Zandschulp said, "but if you want to beat one of these guys, you have to be unbelievably calm and keep your head there, otherwise they will take advantage. ...

"I was defending well and I think I saw some of the stats: I won an unbelievable amount of points (28 of 35) at the net. My coach wanted me to be a little more aggressive and I think I did it really well today."

Alcaraz said of van de Zandschulp, "I think he played great. He didn't make a lot of mistakes that I thought he was going to do, so I was confused a little bit. I didn't know how to manage that. ...

"I didn't feel well hitting the ball. I think I made a lot of mistakes and when I wanted to come back ... it was too late."

van de Zandschulp won 78 percent of his first-serve points and converted six of his nine break-point opportunities.

Earlier Thursday, world No. 1 Jannik Sinner made quick work of 20-year-old American Alex Michelsen, the Italian prevailing 6-4, 6-0, 6-2.

Sinner, who also defeated Michelsen during the Cincinnati Open earlier this month, notched his 50th match win of the season and his 30th on hard courts, most on the ATP Tour.

Sinner saved 3 of 5 break points while converting 8 of 16 chances to break Michelsen's serve en route to victory in a tidy one hour, 39 minutes. He capitalized on Michelsen's 32 unforced errors.

"I am very happy to get through. He is a very tough opponent," Sinner said post-match. "We had a match in Cincinnati one week ago, so I knew a little what to expect."

Sinner's third-round opponent will be Australian Christopher O'Connell, who beat Italian qualifier Mattia Bellucci 6-3, 6-4, 3-6, 6-3.

It wasn't as breezy for other top seeds on Thursday. Australia's Jordan Thompson, unseeded but ranked 32nd in the world, rolled past No. 7 seed Hubert Hurkacz of Poland 7-6 (2), 6-1, 7-5.

Thompson hit 13 aces to just two double faults and won 42 of his 51 first-service points (82.4 percent).

Tomas Machac of the Czech Republic toppled No. 16 seed Sebastian Korda of the U.S. 6-4, 6-2, 6-4 to reach the third round of the U.S. Open for the first time.

"It was pretty difficult. I think I was playing a solid match, so was Sebi at the beginning," Machac said. "At the beginning of the third set, I noticed he was struggling, shaking out his hand, but he was still fighting so much and playing like he wasn't in pain. So I had to be really focused on my tennis."

Canadian qualifier Gabriel Diallo edged No. 24 seed Arthur Fils of France 7-5, 6-7 (3), 6-4, 6-4.

No. 10 seed Alex de Minaur of Australia took care of business against Finnish qualifier Otto Virtanen, 7-5, 6-1, 7-6 (3). No. 25 seed Jack Draper of Great Britain, No. 30 seed Matteo Arnaldi and No. 31 seed Flavio Cobolli, both of Italy, all advanced to the next round.

No. 14 seed Tommy Paul led 7-5, 6-0, 1-0 when Australian opponent Max Purcell retired.

Great Britain's Daniel Evans, two days removed from winning the longest match (five hours, 35 minutes) in U.S. Open history, made quicker work of Argentina's Mariano Navone, 6-4, 6-3, 6-3. Other winners included Nuno Borges of Portugal, David Goffin of Belgium and Jakub Mensik of the Czech Republic.

In nighttime action, No. 5 seed Daniil Medvedev of Russia eliminated Hungary's Fabian Marozsan 6-3, 6-2, 7-6 (5).

--Field Level Media