João Fonseca

Early life

Fonseca was born in Ipanema, Rio de Janeiro, to parents Roberta and Christiano Fonseca. He started taking tennis lessons in his early childhood, at the Rio de Janeiro Country Club, a multi-sports club next to his home.

Career

Juniors

Fonseca reached the final of the boys' doubles category at the 2023 Australian Open with Belgian Alexander Blockx. In March, he was a runner-up at Banana Bowl, a top junior-level event hosted in Criciúma, Brazil. Fonseca, as the fourth seed and home favourite, lost to second seed Yaroslav Demin in the final.

In July, Fonseca won the prestigious U18 grass tournament in Roehampton, England, prior to a run at the 2023 Wimbledon that saw him reach the quarterfinals in singles. He lost to eventual champion Henry Searle. He reached the semifinals in the doubles category, with Bolivian Juan Carlos Prado Ángelo.

Later that season, he won the boys' singles title at the 2023 US Open with a victory over American Learner Tien in the final. With that result, he became the third major junior champion in singles from Brazil, after Tiago Fernandes and Thiago Seyboth Wild.

Fonseca had good results on ITF Junior Circuit, maintaining a 92–27 singles win-loss record. At 17 years old, he was the first Brazilian to finish the season as world No. 1 in the junior rankings on 11 September 2023. He was named the 2023 junior champion by the ITF.

2023: First professional matches, ATP Tour debut

Fonseca made his ATP debut at the 2023 Rio Open after receiving a wildcard for the singles main draw and also appeared in the doubles main draw, entering as lucky losers with Mateus Alves.

2024: First ATP wins, NextGen Finals title

In January 2024, the 17-year-old Fonseca reached the semifinals of the Buenos Aires Challenger, his best performance in this type of tournament. Until then, Fonseca had reached the quarterfinals in two challengers, the first in 2022 in São Leopoldo and the most recent in 2023, in Florianópolis.

Ranked No. 655 that moment, Fonseca made a second appearance in the main draw at the 2024 Rio Open after receiving a wildcard in singles and also in doubles qualifying with Marcelo Zormann. He recorded his first ATP and first ATP 500 win over seventh seed Arthur Fils in straight sets, giving away only four games. Excluding the Davis Cup, he became the first South American to claim an opening set 6–0 against a top 50 ranked opponent before turning 18, since the ATP rankings were first published in 1973. He also became the first player born in 2006 to win an ATP Tour match. Next, he defeated Cristian Garin in straight sets to reach his first ATP quarterfinal. As a result, he moved 300 positions up, making him the youngest player in the top 350 in the rankings. He became the second youngest ATP 500 quarterfinalist since the series began in 2009 and the first since Alexander Zverev made the last eight in Hamburg in 2014.

Days after the end of his run in Rio, Fonseca was rewarded with a second consecutive ATP Tour tournament wildcard at the 2024 Chile Open.

Later that week, he officially announced his decision to fully turn pro, forgoing his eligibility to play college tennis and ending his commitment to the University of Virginia.

In March, at the 2024 Paraguay Open, Fonseca defeated Argentine Román Burruchaga to reach his first ATP Challenger final and made his top 300 debut at world No. 288 on 1 April 2024 moving more than 50 positions up in the rankings. He lost to compatriot Gustavo Heide in the championship match.

Ranked No. 276, Fonseca received a wildcard for the 2024 Țiriac Open in Bucharest, Romania and reached the quarterfinals of an ATP Tour event for the second time, defeating sixth seed Lorenzo Sonego, his third ATP tour win, and fellow qualifier Radu Albot. He lost to fourth seed Alejandro Tabilo. As a result, he reached the top 250 in the rankings.

2025: Major debut & third round, ATP 500 title, Brazilian No. 1, top 25

Fonseca lifted his second Challenger title at his very first tournament of the season, the 2025 Canberra Tennis International, defeating American Ethan Quinn in the final, recording his 10th consecutive win and reaching his new career high ranking at No. 113 on 6 January 2025.

Fonseca qualified for the Australian Open to make his major debut.

He defeated ninth seed Andrey Rublev in straight sets in his first major main draw match for his first top 10 victory, becoming the first teenager since Mario Ančić (against Roger Federer in 2002 Wimbledon Championships) to beat a top 10 player in the first round of a Grand Slam. Fonseca made his Top 100 debut on 27 January 2025, at No. 99. At 18 years 5 months and 6 days, he became the youngest Brazilian to ever do so, surpassing Cássio Motta.

Fonseca became the youngest Brazilian in the Open Era to reach an ATP semifinal, at the 2025 Argentina Open and the first man born in 2006 or later to reach a final. At 18 years 5 months and 26 days, Fonseca became also the tenth-youngest tour-level finalist since 2000, and the youngest South American finalist since former World No. 20 Argentine José Acasuso in 2001. With reaching the final he entered the top 75 in the rankings, becoming the Brazilian No. 1 singles player on 17 February 2025. He lifted his maiden tour-level title with a straight-sets win over Francisco Cerúndolo becoming the youngest Brazilian to win an ATP title in the Open Era. He was also the youngest South American champion and 10th-youngest titlist in ATP Tour era (since 1990).

After that campaign, Fonseca came back to his hometown event at the 2025 Rio Open, where he played in the singles draw and lost to Alexandre Müller in the first round.

Fonseca received a wildcard to the Indian Wells Open, a prestigious Masters 1000-level event. The Brazilian won against Jacob Fearnley in three sets and lost in the second round to the 13th seed and eventual champion Jack Draper.

This early defeat led Fonseca to play the following week in the Arizona Tennis Classic in Phoenix, where he earned his second Challenger singles title – biggest of the series at 175 – for the season, with victories over fourth seed Jan-Lennard Struff, former Top-10 Kei Nishikori and Alexander Bublik in the final. It was also his fourth Challenger title overall. With this trophy, Fonseca became the first player to win ATP 250, Challenger 175 and Challenger 125 titles in the same season.

2026: First ATP Tour doubles title, Masters 1000 quarterfinal, and major quarterfinal

In January 2026, Fonseca was scheduled to start the season by playing at the Brisbane International and face Reilly Opelka on the first round, but due to an injury on his back, he withdrew from that tournament. He would also play at the Adelaide International the following week, but still feeling that injury, he also decided not to play.

Later that month, he participated at the Australian Open as the 28th seed, but lost on the first round to Eliot Spizzirri in four sets.

Fonseca's next tournament of the season was at the Argentina Open in Buenos Aires, where he was the defending singles champion, but could not defend his title due to a loss on the first round to Alejandro Tabilo in three sets.

His next tournament was at the Rio Open, his hometown event, where Fonseca got his first win of the season by beating fellow countryman and qualifier Thiago Monteiro. He lost on the second round to Peruvian Ignacio Buse in three sets. Fonseca also received a wildcard to participate in the doubles event, partnering with compatriot Marcelo Melo. The Brazilian pair reached the final, facing German Constantin Frantzen and Dutch Robin Haase. That was the first time on Fonseca's career that he reached a doubles final on any ATP tournament. Fonseca and Melo ended up winning that final, securing his first ever doubles title on the ATP Tour. As a result, Fonseca also achieved his best doubles ranking at that moment, No. 160.

Fonseca arrived at the Indian Wells Open unseeded. Despite this disadvantage, he collected victories against 16th seed Karen Khachanov and 23rd seed Tommy Paul to reach the Round of 16, where he lost to world No. 2 Jannik Sinner in two tie-breaks.

In early April, Fonseca played in Monte Carlo, Monaco for the first time. At that tournament, he became the second player born in 2006 to reach the quarter-finals of a Masters, with victories over Gabriel Diallo, Arthur Rinderknech and Matteo Berrettini. He lost to third seed Alexander Zverev in three sets.

Personal life

Fonseca's father is CEO and co-founder of IP Capital Partners, the first independent hedge fund in Brazil. His mother is a former volleyball player.

Performance timeline

Singles

Current through the 2026 Cincinnati Open.

ATP Tour finals

Next Gen ATP finals

ATP Challenger finals

ITF World Tennis Tour finals

National and international representation

Laver Cup

indicates the result of the Laver Cup match followed by the score, date, place of event and the court surface.

Junior Grand Slam finals

Wins over top 10 players

Fonseca has a 2–6 record against players who were, at the time the match was played, ranked in the top 10.

Key: (Rk) first use, opponent rank; (Rd) round; (Rk) 2nd use, player rank; (Ref) reference; (F) final; (SF) semifinal; (QF) quarterfinal; (#R) rounds 4, 3, 2, 1; (RR) round-robin stage; (Q#) qualifying rounds or stages (3), 2, 1.

Records

These records were attained in the Open Era of tennis.

Exhibition matches

Singles

* non-standard tennis sets

Awards

2023

ITF Junior World Champion

2025

Troféu ACEESP – Esportista Masculino do Ano

Prêmio Brasil Olímpico – Atleta Masculino da Torcida (Fan's Choice)