NEW YORK — Carlos Alcaraz’s 15-match Grand Slam unbeaten run ended with a 6-1, 7-5, 6-4 loss to No. 74 Botic Van De Zandschulp in the second round on Thursday night at the US Open. It was a stunning result that eliminated the pre-tournament favorite.

This match was difficult to predict given Alcaraz’s standing in the sport, his recent achievements and his opponent’s much lesser resume.

Alcaraz won Roland Garros in June and Wimbledon in July, giving him four major championships to his name in his career. He will also win the title at Flushing Meadows in 2022.

But he never found his groove against Van De Zandschulp, a 28-year-old Dutchman. Alcaraz was way off the mark, repeatedly missing the kind of shots he normally makes routinely. After double-faulting and falling two sets to none behind — a deficit he never recovered from — the third-seeded Alcaraz slung his gear bag over his shoulder and trudged to the locker room.

Alcaraz looked toward his coach, 2003 French Open winner Juan Carlos Ferrero, and pointed his right index finger toward his temple. He then waved the finger as if to say, “I’m not thinking clearly.”

He could be forgiven for being confused by what was happening under the closed retractable roof of Arthur Ashe Stadium on a cold evening.

The 21-year-old Spaniard entered the US Open with a 16-2 record, having never lost before the quarterfinals in three previous appearances. It was also Alcaraz’s first defeat at a major tournament since exiting in the second round of Wimbledon as a teenager in 2021; he has never lost in the first round at a Grand Slam event.

Van De Zandschulp, on the other hand, has only reached the quarter-finals of a Grand Slam once, namely at the US Open in 2021.

Otherwise, though, he’s not someone most people would have expected to pull off this kind of monumental upset. Consider: Van De Zandschulp was only 11-18 for the season at the start of this week and hadn’t won consecutive matches at a tour-level event in 2024.

“I’m actually a little speechless,” he said. “It was an incredible night for me.”

That was certainly the case.

The most important statistic was probably that Van De Zandschulp managed to score 28 of his 35 goals.

The opening set was lopsided. With Van De Zandschulp’s powerful forehands and serves of up to 132 mph finding their mark, Alcaraz never seemed to get comfortable, even though he had won their last two matchups.

Alcaraz failed to produce a winner in that set and nearly doubled his points total, 24-13. The second set was a little better for him, but not enough, and a double fault wrapped up a service break that put Van De Zandschulp up 6-5. When Alcaraz pushed a forehand wide to end the next game, Van De Zandschulp completed a hold at love that gave him the first two sets after 1 1/2 hours of action.

It didn’t take long for Alcaraz to find himself a break behind in the third set as well, 3-2, but he immediately made a fist – well, with some help, as Van De Zandschulp’s double fault resulted in a break that made it 3-3. Alcaraz then held at love and smiled as he headed for the changeover.

However, that grin quickly disappeared as Alcaraz continued to make mistakes and Van De Zandschulp never gave up.

“Of course I was a bit nervous, but I think if you want to beat one of these guys you have to keep your cool and keep your head in the game,” said Van De Zandschulp, who will face 25th-seeded Jack Draper of Great Britain in the third round on Saturday. “Otherwise they will take advantage of it.”

Alcaraz is the first top-three seed to lose within the first two rounds of the US Open since 2006, when third-seeded Ivan Ljubicic lost in the first round to Feliciano López.

Alcaraz began the night 25-1 in majors against players ranked outside the top 50, with his only loss coming to No. 95 Mikael Ymer in the second round of the 2021 Australian Open.

The Associated Press and ESPN Stats and Information contributed to this report.