João Fonseca (tennis)

2.1. Junior Career

In 2023, Fonseca reached the final of the boys' doubles at the 2023 Australian Open Junior Championships, where he partnered with Belgian player Alexander Blockx. Later that year, he achieved a major milestone by becoming the boys' singles champion at the 2023 US Open Junior Championships, defeating American player Learner Tien in the final. His success on the junior circuit led him to be crowned the 2023 world champion of the Junior circuit. At 17 years old, he made history as the first Brazilian to conclude the season as the No. 1 ranked player in the ITF junior rankings.

2.2. Professional Debut and Early Success (2023-2024)

Fonseca made his ATP Tour debut in 2023 at the 2023 Rio Open, where he received a wildcard entry into the singles main draw. He also competed in the doubles main draw as a lucky loser alongside Mateus Alves.

The year 2024 marked a period of significant progress for Fonseca. In January, at 17 years old, he reached the semifinals of the Buenos Aires Challenger, which was his first semifinal appearance in this type of tournament. Previously, he had reached the quarterfinals at two Challengers, in São Leopoldo in 2022 and Florianópolis in 2023.

Ranked No. 655, Fonseca received another wildcard for the main draw of the 2024 Rio Open in singles, and also participated in doubles qualifying with Marcelo Zormann. At this tournament, he secured his first ATP Tour victory, and notably, his first win at an ATP 500 event, defeating the seventh seed Arthur Fils in straight sets while dropping only four games. This win made him the first South American player to claim an opening set 6-0 against a top 50 ranked opponent before turning 18 since the ATP rankings began in 1973, excluding Davis Cup matches. He also became the first player born in 2006 to win an ATP Tour match. Following this, he went on to defeat Cristian Garin in straight sets to reach his first ATP quarterfinal. As a result, his ranking soared by 300 positions, making him the youngest player in the top 350. He became the second youngest ATP 500 quarterfinalist since the series began in 2009, a feat not seen since Alexander Zverev reached the last eight in Hamburg in 2014.

Shortly after his successful run in Rio, Fonseca was granted a second consecutive ATP Tour wildcard for the 2024 Chile Open. In the same week, he officially declared his decision to turn professional, opting to forgo his college tennis eligibility and ending his commitment to the University of Virginia.

In March, at the 2024 Paraguay Open, Fonseca defeated Argentine player Román Andrés Burruchaga to reach his first ATP Challenger final. This achievement propelled him into the top 300, reaching world No. 288 on April 1, 2024, after climbing more than 50 positions. He ultimately lost the championship match to his compatriot Gustavo Heide.

Ranked No. 276, he received a wildcard for the 2024 Țiriac Open in Bucharest, Romania. There, he 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 was eventually defeated by fourth seed Alejandro Tabilo. This performance helped him enter the top 250 in the rankings.

Fonseca received a wildcard for the main draw of the 2024 Madrid Open, marking his debut at an ATP Masters 1000 event. He secured his first win at this level by defeating American player Alex Michelsen.

At the start of the grass season, ranked No. 217, he also received a wildcard for the main draw of the 2024 Halle Open. He continued to climb the rankings, reaching No. 166 on August 5, 2024, after winning his maiden Challenger title at the 2024 Lexington Challenger. At 17 years old, he became the youngest Challenger champion of the 2024 season.

Fonseca qualified for the 2024 Next Generation ATP Finals on November 29, 2024. Despite being the lowest-ranked player in the field, he went on to win the title, completing a perfect run through the tournament.

2.3. Breakthrough Year and First ATP Title (2025)

Fonseca started 2025 strong by winning his second Challenger title at the 2025 Canberra Tennis International, his very first tournament of the season. He defeated American Ethan Quinn in the final, marking his 10th consecutive win and achieving a new career-high ranking of No. 113 on January 6, 2025.

Fonseca successfully qualified for the Australian Open, making his major debut. In his first major main draw match, he delivered a stunning upset, defeating ninth seed Andrey Rublev in straight sets to secure his first top 10 victory. This made him the first teenager since Mario Ančić (who defeated Roger Federer at 2002 Wimbledon Championships) to beat a top 10 player in the first round of a Grand Slam. On January 27, 2025, Fonseca made his debut in the ATP top 100, reaching No. 99. At 18 years, 5 months, and 6 days old, he became the youngest Brazilian male tennis player to achieve a top 100 ranking, surpassing the record previously held by Cássio Motta.

João 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 old, Fonseca also became the tenth-youngest tour-level finalist since 2000, and the youngest South American finalist since the 18-year-old Argentine José Acasuso in 2001. By reaching the final, he broke into the top 75 in the rankings, becoming the No. 1 Brazilian singles player on February 17, 2025. He went on to lift his maiden tour-level title with a straight-sets victory over Francisco Cerúndolo, making him the youngest Brazilian to win an ATP title in the Open Era. He was also the youngest South American champion and the 10th-youngest titlist in the ATP Tour era (since 1990).

Following this successful campaign, Fonseca returned to his hometown event at the 2025 Rio Open, where he participated in the singles draw but was defeated by Alexandre Müller in the first round.

3.1. Singles

Current through the 2025 Rio Open.

4.1. ATP Tour Singles Finals

4.2. ATP Next Generation Finals

4.3. ATP Challenger Tour Finals

João Fonseca has competed in three singles finals and one doubles final on the ATP Challenger Tour, securing two singles titles and one doubles title.

4.4. ITF World Tennis Tour Finals

6.1. Singles: 1 (1 title)

6.2. Doubles: 1 (1 runner-up)