In my previous article, I reviewed the five biggest upsets on the ATP tour this year, excluding Grand Slam events due to their distinct status.
Compared to the best-of-three format in other tour events, the best-of-five format in Grand Slams seems to make upsets harder to come by. Yet, four of the five key players involved in this year’s biggest Grand Slam surprises have all been Grand Slam finalists and ranked within the top five, but were nonetheless upset, highlighting the dangers of Grand Slam competition. Here they are:

5⃣️ French Open Second Round: Gigante 6-4, 5-7, 6-2, 6-4 over Tsitsipas
Tsitsipas, a confirmed clay-court specialist with three Monte Carlo Masters titles in the past five seasons, once led Djokovic by two sets in the French Open final, just inches from his first Grand Slam crown.
Although he exited early at the Australian Open this year and showed only average form in the clay Masters events before Roland Garros, no one expected him to bow out so early in the second round of the French Open, failing even to reach a deciding set.
Tsitsipas’s slump this year was somewhat predictable; despite breaking his 500-match title drought in Dubai, personal setbacks off the court appeared to affect his performance on it.

4⃣️ US Open Second Round: Corentin Moutet 6-4, 3-6, 3-6, 6-4, 7-5 over Ruud
Ruud, last year’s finalist, finally captured his first Masters title in Madrid during the first half of the year, but a disastrous second half saw his ranking plummet. While his lack of motivation on grass was understandable, an early second-round exit at the US Open was still unexpected.

3⃣️ Wimbledon First Round: Lindgren 7-6(3), 6-7(8), 6-3, 6-7(5), 6-4 over Zverev
Another highlight from this year’s Shanghai Masters runner-up! Lindgren pushed Zverev to five sets in the first round of Wimbledon and prevailed. After Zverev’s runner-up finish at the Australian Open, his other results have been mediocre.
2⃣️ Australian Open First Round: Fonseca 7-6(1), 6-3, 7-6(5) over Rublev
This Brazilian rising star, likely to win the Most Improved Player award, stunned fans by defeating Rublev in straight sets in the first round of the Australian Open, setting the stage for his later dual titles this season.

1⃣️ Australian Open Second Round: Learner Chen 6-3, 7-6(4), 6-7(8), 1-6, 7-6(10-7) over Medvedev
Despite missing out on a nomination for the Most Improved Player award and facing criticism from some media and fans, this American youngster showed immense potential and strong performance. In a five-set thriller, he battled Medvedev—known for his endurance—right to the final point and won, making him the opponent Medvedev least wants to face in the upcoming season. (Source: Tennis Home, Author: Luo Cheng Qiye)