ATP Tour
#NextGenATP talents Fonseca, Mensik, Tien headline first-time ATP Tour winners in 2025
Muller, Machac, Cobolli, Brooksby, Diallo, Vacherot all feature in nine-player list
December 11, 2025
Marcelo Endelli/Getty Images
Joao Fonseca triumphs in Buenos Aires for his first ATP Tour title.
By Jerome Coombe
To mark the end of another thrilling season, ATPTour.com is unveiling our annual ‘Best Of’ series, which will reflect on the most intriguing rivalries, matches, comebacks, upsets and more. Today we highlight those who joined the winner’s circle for the first time.
The 2025 ATP Tour ushered in a fresh cast of first-time champions, nine players who carved their names onto the winners’ roll and into the season’s defining narrative. It was a year marked by unexpected breakthroughs, dramatic runs, and stories that captured the imagination of fans around the world.
Alexandre Muller, Hong Kong
The Frenchman opened the new season with a nerve-jangling surge to the Bank of China Hong Kong Tennis Open crown. After beating Kei Nishikori in the final, Alexandre Muller became just the third player in the Open Era to win a tour-level title having lost the opening set in every match he played (after Arthur Ashe at the 1975 WCT Finals and Alexander Bublik in Montpellier in 2024).
“I was a little tired on the courts but I think the key was to stay calm and keep the energy for myself,” Muller said. “I stayed calm, focused on my game and tried to adapt.”
Joao Fonseca, Buenos Aires
After his triumph at last year’s Next Gen ATP Finals presented by PIF in Jeddah, Joao Fonseca arrived in 2025 surrounded by expectation, and he instantly delivered. The 18-year-old produced a dazzling run at the IEB+ Argentina Open — including against Mariano Navone in the quarter-finals, where he saved two match points — to become the youngest South American champion in the ATP Tour era (since 1990).
“Unbelievable week, even in Argentina there are some Brazilians cheering for me,” an emotional Fonseca said. “That’s just amazing. Every Brazilian, everyone from their country wants this support from your own country. For me, this [moment] that I’m living is just unbelievable.”
Tomas Machac, Acapulco
Tomas Machac arrived at the Abierto Mexicano Telcel presentado por HSBC in Acapulco as the highest-ranked player yet to win a title, but he left with an ATP 500 trophy in his hands. His championship-match victory placed him alongside former Top 10 stars Tomas Berdych and Radek Stepanek as the only Czech players to win a title at that level.
“It means a lot. It is something I never dreamed could happen, especially at an ATP 500, so it feels amazing for me,” said Machac, who rose five spots to No. 20 with his triumph. “I was working very hard in the past year, so I am happy I can achieve something that shows me I am going the right way.”
Jakub Mensik, Miami
Facing Novak Djokovic in an ATP Masters 1000 final would intimate almost anyone. But not Jakub Mensik, who delivered the performance of his career at the Miami Open presented by Itau, where the 19-year-old downed his idol in straight sets to become just the fourth man to win his first ATP Tour title at that level.
“It was not the first time I’ve played against Novak,” said Mensik, who lost his first Lexus ATP Head2Head meeting Djokovic last year in the Shanghai quarter-finals. “There is no harder task in tennis than to beat him in the finals. But of course I felt really great and it’s my time, so I just tried to focus on the match like I did before in previous rounds.”
Flavio Cobolli, Bucharest
Flavio Cobolli flipped his 2025 season on its head in spectacular fashion at the Tiriac Open presented by UniCredit Bank. The Italian arrived in Bucharest riding an eight-match tour-level losing streak, but he tore through the field — including top seed Sebastian Baez in the final — to join the ATP Tour winner’s circle.
“It’s a big dream come true for my career,” said Cobolli. “I always dreamed of winning an ATP tournament and it happened today. I came from a tough moment. I had not won a match before this tournament, this year, and I won the tournament. So I’m really happy about it.”
Jenson Brooksby, Houston
If drama defined Muller’s run in Hong Kong, Jenson Brooksby’s week at the Fayez Sarofim & Co. U.S. Men’s Clay Court Championship in Houston was downright cinematic. The 24-year-old American saved match points in three of his matches en route to his maiden title. He survived one in his first-round qualifying match, two against third seed Alejandro Tabilo in the main-draw second round, and one against top seed Tommy Paul in the semi-finals, before defeating 2023 Houston champ Frances Tiafoe 6-4, 6-2 in the final. Brooksby began the season as an unranked player but in Houston, where he was competing as the World No. 507, he became the third-lowest ranked champion in ATP Tour history (since 1990).
“It means the world. It was one of my biggest goals ever since I’ve been a professional tennis player,” said Brooksby, who entered the ATP 250 as a qualifying wild card. “It just means a lot to have my first one. It really does. It’s probably the best week of my life.”
Gabriel Diallo, ‘s-Hertogenbosch
At the Libema Open, Gabriel Diallo showcased his natural feel for grass, launching 56 aces on his way to the title at the ATP 250 in ‘s-Hertogenbosch. He edged close friend Zizou Bergs 7-5, 7-6(8) in a tense final before collapsing in delighted disbelief.
“Oh man, I don’t have the words. It’s something that you dream of for your whole life since you were a little kid, to get an ATP Tour title,” said Diallo, who lost his first tour-level final in Almaty in 2024. “The fact that I was able to do it here after losing a final last year, it just means the world to me. I’m very happy, not only for myself but for my whole team.”
Valentin Vacherot, Shanghai
Valentin Vacherot produced one of the season’s most astonishing runs at the Rolex Shanghai Masters. As the No. 204 player in the PIF ATP Rankings, he became the lowest-ranked ATP Masters 1000 champion, defeating the likes of Holger Rune and Djokovic before his cousin and former Texas A&M teammate Arthur Rinderknech in a family-driven final.
“It is unreal what just happened. I have no idea what is happening right now. I am not even dreaming, it is just crazy,” Vacherot said after the final. “I am just so happy with my performances the past two weeks. There has to be one loser but I think there are two winners today, one family that won. And I think for the sport of tennis, the story is unreal.”
Learner Tien, Metz
In the closing week of the regular ATP Tour season, Learner Tien delivered a defining moment at the Moselle Open in Metz. The 19-year-old added a maiden tour-level trophy to a year in which he captured five Top-10 wins and reached an ATP 500 final in Beijing.
“I never take it for granted, just coming out here and competing. So, holding this trophy just means the world to me. And I’m just really grateful,” Tien said during the trophy ceremony.
