#NextGenATP Talents Tien & Fonseca Shock the Tennis World with Epic Grand Slam Upsets
Featuring Gigante, Collignon, and Rinderknech in the Top 5 shout-out!
November 30, 2025
Daniel Pockett/Getty Images
Learner Tien claims victory against Daniil Medvedev in a nail-biting five-set match at the Australian Open.
By Jerome Coombe
As we wrap up an exhilarating season, ATPTour.com proudly presents our annual ‘Best Of’ series, spotlighting the most captivating rivalries, epic matches, thrilling comebacks, and stunning upsets. Today, we reminisce on five unforgettable Grand Slam upsets from this remarkable season.
Overcoming a top player is impressive, but doing it on their favored surface, in front of a raucous crowd — or even during your inaugural Grand Slam match — is truly monumental.
From emerging teens dismantling top seeds to qualifiers defying all odds on the grandest stages of tennis, the 2025 majors brought forth dramas that couldn’t be scripted. In our season retrospective, ATPTour.com presents the five most shocking Grand Slam upsets of the year.
5) Roland Garros R2: Gigante d. Tsitsipas 6-4, 5-7, 6-2, 6-4
Stefanos Tsitsipas had always relished the challenge at Roland Garros, but Matteo Gigante had other plans.
Unexpectedly cracking through at No. 167 in the PIF ATP Rankings, the Italian qualifier played with the thrill of a competitor who had nothing to lose, using his dynamic lefty forehand to topple the 2021 finalist in four gripping sets. This loss marked a painful juncture for Tsitsipas, his first departure from the Top 20 since 2018.
Gigante’s progression to the third round became a defining moment in his career as he climbed to a personal-best ranking of World No. 125, in pursuit of breaking into the Top 100.
Matteo Gigante celebrates his first Top 20 victory over Stefanos Tsitsipas at Roland Garros. Photo: Adam Pretty/Getty Images.
4) US Open R2: Collignon d. Ruud 6-4, 3-6, 3-6, 6-4, 7-5
For Raphael Collignon, New York transformed from a dream into a reality.
A broken thumb had initially derailed his hopes of direct entry to Roland Garros, but his journey in the US Open was nothing short of historic as he claimed his first-ever main-draw victory at a major against 2022 finalist Casper Ruud after an exhilarating battle lasting three hours and 28 minutes.
“I think it’s the best day of my life,” said Collignon. “Casper is a phenomenal player, and I had to overcome fear to find my rhythm.”
Despite serving three double faults while trying to close out the match, Collignon eventually sealed the deal on his third match point. This victory propelled him back into the Top 100, setting him on a path to finish the year strong.
Raphael Collignon achieves a milestone by reaching the third round at a Grand Slam for the first time. Photo: Matthew Stockman/Getty Images.
3) Wimbledon R1: Rinderknech d. Zverev 7-6(3), 6-7(8), 6-3, 6-7(5), 6-4
After a marathon that stretched for four hours and 44 minutes on Centre Court, Arthur Rinderknech authored a masterpiece against third seed Alexander Zverev.
Rinderknech unleashed 79 winners, showcasing relentless boldness and securing his maiden victory over a Top 5 player. This upset galvanized a spectacular second half of his season, leading to a semi-final run in Gstaad and a last-16 appearance at the US Open. He later triumphed in his first ATP Masters 1000 final in Shanghai, further solidifying his place in the sport.
“It was a watershed moment, probably my best on-court experience,” Rinderknech reflected in October. “After that win, everything fell into place.”
Arthur Rinderknech celebrates defeating Alexander Zverev at Wimbledon. Photo: Corinne Dubreuil.
2) Australian Open R1: Fonseca d. Rublev 7-6(1), 6-3, 7-6(5)
Joao Fonseca entered the Australian Open as one of the most promising new stars, but defeating a seasoned expert like Andrey Rublev was another level.
Nevertheless, Fonseca’s calculated aggression and powerful forehand propelled him through the first round in straight sets, sending shockwaves through Margaret Court Arena and igniting fervor on social media. For the 18-year-old Brazilian, this victory was a testament to his rapid rise following a stellar 2024 season.
“I aimed to keep my composure playing against a Top 10 player in a big stadium,” Fonseca said. “[I wanted] to rally the crowd behind me, and I truly immersed myself in my game.”
Joao Fonseca achieves a remarkable victory against Andrey Rublev at the Australian Open. Photo: William West/Getty Images.
While Fonseca faced a setback in his second round against Lorenzo Sonego, he continued to shine throughout the 2025 season, clinching his first ATP Tour title in Buenos Aires and later winning an ATP 500 crown in Basel — a historic feat as the first Brazilian to secure a title above ATP 250 since Gustavo Kuerten in 2001.
1) Australian Open R2: Tien d. Medvedev 6-3, 7-6(4), 6-7(8), 1-6, 7-6(10-7)
Margaret Court Arena bore witness to one of the season’s greatest shocks as American teenLearner Tien marked his ascent with a hard-fought triumph over the three-time Australian Open finalist Daniil Medvedev.
Despite being ranked World No. 121, Tien faced heartbreak after failing to capitalize on a match point in the third set. The tension reached its peak as Medvedev served for the match at 6-5 in the fifth, but Tien displayed unwavering determination to claw back and secure the watershed victory at 2:54 a.m. local time.
“I was really hoping to avoid a fifth-set tie-break, but I’m just thankful for the win,” Tien expressed. “I probably made it more challenging than necessary… Losing the third set was tough after the long battle.”
Learner Tien celebrates his victory over Daniil Medvedev at the Australian Open. Photo: Paul Crock/Getty Images.
Following that unforgettable match, Tien’s trajectory soared, solidifying his status at the tour level. Together with Fonseca, who previously edged out Tien in the 2024 Next Gen ATP Finals presented by PIF, Tien established his presence with five Top-10 victories throughout 2025 and clinched his first ATP Tour title in Metz in November.
