Three biggest upsets on Day 4 of US Open

On Day 4 of the 2024 US Open, Iga Swiatek and Jannik Sinner flashed their World No. 1 form with dominant performances that moved them into the third round. It was a joyous day for the Americans as home stars Tommy Paul and Jessica Pegula punched their tickets into the Round of 32.

The day was also marred by an unfortunate walkover as World No. 4 and fan-favorite Elena Rybakina withdrew from her match against France's Jessika Ponchet with a lower back injury.

And, of course, there were several monumental upsets along the way.

World No. 7 Hubert Hurkacz (Poland)

A second-round tie against an unseeded doubles specialist, Jordan Thompson? This was projected to be a breeze for Hurkacz, the Pole who famously ended Roger Federer's storied Wimbledon career. And it appeared to be just that when he jumped into a 5-3 lead in the first set. That was until the Aussie broke Hurkacz's serve four consecutive times to take the opening set, 7-6 stunningly. Thompson remained the aggressor, winning the second set 6-1 before finishing off the Pole 7-5 for a straight sets win.

Despite being down two sets, Hurkacz had the chance to claw back when he notched up two set points up 5-4 in the third. However, Thompson remained poised by striking a bold forehand winner to hold serve before breaking Hurkacz again. The play summed up the match, which saw Thompson convert on 50 percent of his break points while Hurkacz converted on only 30 percent of those opportunities.

Thompson will face Italy's Matteo Arnaldi in the third round.

World No. 3 Carlos Alcaraz (Spain)

In what is being deemed the biggest upset of 2024, Carlos Alcaraz's 15-match winning streak at major events ended courtesy of the Netherlands' Botic van de Zandschulp, who stunned the Spaniard in straight sets, 6-1, 7-5, 6-4, to advance to the third round at Flushing Meadows.

The early exit meant Alcaraz wouldn't join Rod Laver and Rafael Nadal on the list of players to win the French Open, Wimbledon, and US Open in the same calendar year. The loss also marked his earliest at a major since he bowed out in the second round of the 2021 Wimbledon as a teenager.

Alcaraz — who committed 27 unforced errors — admitted that he never felt himself throughout the match, evident when he quickly went down 4-1 in the opening set. Van De Zandschulp kept attacking the net, where he converted 28/35 points, forcing the Spaniard to switch strategy and move away from his thunderous baseline strokes. However, Alcaraz lacked the accuracy and high-end shotmaking that helped him capture four majors at age 21. He even hinted at feeling a mental burnout after he lost to Novak Djokovic in the gold-medal game at the Paris Olympics.

In the third round, Van de Zandschulp will face Great Britain's Jack Draper.

Wild card Naomi Osaka (Japan)

Why is a wild card entrant on this list? Simple: Osaka's a former four-time major winner and two-time US Open champion. And she was going up against the unseeded Karolina Muchova, who entered the match with a 6-5 singles record in 2024. Osaka was the clear favorite here.

Muchova won the contest with her confident play at the net. When the opening set was tied 3-3, the Czech journeywoman made the bold call to charge the net and execute a surprise drop shot, catching Osaka off guard. She continued to resort to the strategy, quickly jumping 5-3 ahead before Osaka was broken for the second time. In the second set, Osaka was a point away from pushing the contest to a decider while serving at 5-4. However, she would miss two forehands to cede the game, causing her to chuck the racket in frustration. Muchova pulled off the win in the ensuing tiebreaker.

Ultimately, the match was decided at the net, where Muchova won 68 percent of her points compared to Osaka's 44. It was apparent that the latter was still working herself back to her ideal physical form.

Despite the loss, Osaka has ample reason to feel optimistic about her return to the Tour. In her first US Open in four years — she missed most of 2022 and 2023 with injuries and maternity leave — she showed flashes of the player who dominated the Tour just a few years ago. She just needs reps. If she wins a slam or two in 2025, it shouldn't be a shock.