Yosuke Watanuki

On the junior tour, Watanuki has a career high combined ranking of No. 2 achieved on 21 March 2016. Watanuki was the winner of the 2016 Campeonato Internacional Juvenil de Tenis de Porto Alegre, a Grade A event in Porto Alegre, Brazil.

He made his ATP and ATP 500 debut at the 2018 Citi Open after qualifying.

Watanuki first main draw match victory on the ATP Tour came at the 2018 Rakuten Japan Open over Robin Haase as a qualifier.

He won his maiden title at the 2019 Kobe Challenger.

Watanuki entered the 2021 Winston-Salem Open as a lucky loser and won his first match against Jaume Munar. He lost to Márton Fucsovics in the second round.

He reached the quarterfinals of an ATP tournament for the first time in his career, winning his first two matches in a row at this level, as a lucky loser at the 2022 ATP Lyon Open. First he defeated eight seed Pedro Martínez for his second top-50 win. Next he defeated Kwon Soon-woo to set up a quarterfinal with Alex de Minaur. As a result, he returned to the top 225 in the rankings climbing 40 positions in the rankings at world No. 223 on 23 May 2022.

He qualified for his third ATP 500 at the 2022 Citi Open in Washington, D.C., and second time at this tournament, but lost to Kyle Edmund who was playing his first singles match after his comeback.

In November he won two back-to-back titles in Japan at the Hyōgo Noah Challenger in Kobe and in Yokkaichi defeating Frederico Ferreira Silva in both and moved into the top 150 at world No. 145 on 28 November 2022.

In January, Watanuki qualified for the 2023 Australian Open to make his Grand Slam debut. He beat Arthur Rinderknech in the first round in straight sets for his first Major win before losing to Sebastian Korda.

Watanuki qualified for his first Masters 1000 2023 Miami Open and won his first round match against fellow qualifier Benoît Paire but lost to 12th seed Frances Tiafoe. As a result, he moved to a new career high ranking of No. 107 on 3 April 2023. Ranked No. 117, he also qualified for his second Masters at the 2023 Mutua Madrid Open and defeated Corentin Moutet in the first round before losing to world No. 13 and 11th seed Cameron Norrie.

At the 2023 BOSS Open he qualified and won his first round match against wildcard Feliciano López. He entered the main draw at the 2023 Wimbledon Championships as a lucky loser for the first time at this Major and defeated Marc-Andrea Huesler in a five set match for his second Major win. As a result, two weeks later, he reached the top 100 at world No. 99 on 31 July 2023.

At the 2023 Rolex Shanghai Masters he defeated wildcard Juncheng Shang to reach the second round for the third time at a Masters level in the season. As a result, he rose into the top 75 in the rankings on 16 October 2024. He received a wildcard for the main draw at the ATP 500 2023 Japan Open in Tokyo. He finished the 2023 season ranked inside the top 100 at world No. 99.

In September 2024, ranked No. 338 he again received a wildcard in Tokyo, this time for the qualifying competition.^[] Next entered the qualifying rounds of the Shanghai Masters in October 2024 using a protected ranking, and qualified for the main draw after beating Otto Virtanen and Hong Seong-chan.^[] In the main draw, he upset Pavel Kotov and 32nd seed Brandon Nakashima to reach the third round.^[] As a result, he returned to the top 300 of the singles rankings.^[]