Joao Fonseca

Fonseca reached the final of the 2023 Australian Open – Boys' doubles tournament with Alexander Blockx, João Fonseca became the Junior champion of the 2023 US Open - Boys' singles tournament with a victory over Learner Tien in the final.

Fonseca was the 2023 world champion of the Junior circuit. At 17 years old, he was the first Brazilian to finish the season as No. 1 in the junior rankings.

He 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.

In January 2024, the 17-year-old Rio native reached the semifinals of the Buenos Aires Challenger, his first in his career 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, he 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, he 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. Fonseca received a wildcard for the main draw of the 2024 Madrid Open, making his debut at a Masters 1000 and defeated American Alex Michelsen, recording his first win at this level. Ranked No. 217, at the beginning of the grass season, he also received a wildcard for the main draw of the 2024 Halle Open. He reached the top 175 at world No. 166 on 5 August 2024, climbing close to 50 positions up, following lifting his maiden Challenger title at the 2024 Lexington Challenger. At 17 years old, he was the youngest Challenger champion of the 2024 season.

Fonseca qualified for the 2024 Next Generation ATP Finals on 29 November 2024. Although the lowest ranked player, he won the title.

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 number 9 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 Ancic (against Roger Federer in 2002 Wimbledon Championships) to beat a top 10 player in the first round of a Grand Slam.

After losing a tight contest in the second round to No. 55 Lorenzo Sonego, Fonseca is expected to make his Top 100 debut on 27 January 2025; at 18 years 5 months 6 days old, he will become the youngest Brazilian to ever do so, surpassing Cássio Motta by two days.