Leandro Riedi

As a junior, Riedi reached as high as world No. 6 in the combined singles and doubles ITF Junior Circuit rankings, which he attained on 12 October 2020.

With Romanian partner Nicholas David Ionel, he captured the 2020 Australian Open – Boys' doubles title by defeating Mikołaj Lorens and Kārlis Ozoliņš 6–7^(8–10), 7–5, [10–4] in the final. He also reached the boys' singles final at the 2020 French Open, losing to compatriot Dominic Stricker 2–6, 4–6.

Riedi reached five finals on the ITF Men's World Tennis Tour, winning three and losing two. In May, he won the first doubles title of his career, with Dominic Stricker, when they won the M15 Majadahonda tournament on clay courts in Spain. In October, he won his first singles title at the M15 Selva Gardena tournament on hard courts in Italy.

Riedi made his ATP debut at the 2021 Swiss Open Gstaad, receiving a wildcard in both the singles draw and the doubles draw with Jakub Paul. He lost the singles in the first round against Federico Delbonis in straight sets.

In March, he reached his first singles and doubles finals on the ATP Challenger Tour, both at the 2022 Challenger Città di Lugano, Switzerland. He also received a wildcard for the 2022 Geneva Open for the singles and doubles, partnering with Jakub Paul. In the same month, he also won the M25 tournament in Trimbach, Switzerland and in May another M25 in Notthingham, United Kingdom.

In October, in doubles he won the Challenger tournament at Tiburon, California with Valentin Vacherot. In November, he won the 2022 HPP Open Challenger in Helsinki as a qualifier defeating Dimitar Kuzmanov and Jelle Sels, moving 80 positions up in the rankings, finishing the year in the top 200 at No. 197 on 21 November 2022. A week earlier, he reached the top 250 in doubles. The following week he won his next Challenger singles title in Andria, moving up 36 positions to No. 161 on 28 November 2022.

He reached the top 150 on 9 January 2023 at world No. 135 following a final showing at the Challenger in Canberra, Australia. At the 2023 Open 13 Provence in Marseille, he recorded his first ATP win against Arthur Rinderknech. He lost to eventual champion Hubert Hurkacz.

He made his Masters main draw debut in Indian Wells as a qualifier where he lost to Jack Draper. He reached a new career-high of No. 126 on 20 March 2023.

In July at the 2023 Hopman Cup, Riedi upset world No. 6 Holger Rune in straight sets. In October, he received a wildcard for his home tournament the 2023 Swiss Indoors but lost to wildcard and eventual champion Félix Auger-Aliassime.

In January, he won back-to-back Challenger titles in Oeiras, Portugal and in Ottignies-Louvain-la-Neuve, Belgium defeating in the latter, world No. 40 Borna Ćorić for the title, his highest win by ranking thus far, and returned to the top 175 on 29 January 2024. In September, he suffered a knee injury which put an early end to his season. He subsequently underwent surgery.

Riedi underwent another surgery in January but still made his major debut after qualifying for the main draw at the 2025 Wimbledon Championships. Although he lost to fellow qualifier, major debutant, and local player Oliver Tarvet in the first round, he still rose more than 75 positions up back into the 500 on 14 July 2025.

Ranked No. 435 at the US Open, Riedi qualified for the main draw and recorded his first Grand Slam win over Pedro Martínez. He defeated 19th seed Francisco Cerúndolo in a five-set match, becoming the lowest-ranked player in 25 years (since Danny Sapsford at 1999 Wimbledon) to reach the third round of a major. Following his win over Kamil Majchrzak by retirement, he became the lowest-ranked player to reach a major fourth round since Richard Krajicek at the 2002 Wimbledon Championships, and the lowest-ranked player to do so at the US Open since Jay Berger in 1985. As a result he returned to the top 175 in the singles rankings on 8 September 2025. Riedi ultimately lost to Alex de Minaur in the fourth round.