Sayaka Ishii

is a Japanese professional tennis player. She has career-high rankings of world No. 188 in singles, achieved on 17 March 2025, and No. 285 in doubles, achieved on 19 May 2025.

Early life Ishii was born in Shibuya, Tokyo. Her father, Takuro Ishii, is a former professional baseball player, and her mother, , is a former Fuji Television announcer. She trained at the IMG Academy in Bradenton, Florida.

Career

Junior years In 2022, she reached the final of the Osaka Mayor's Cup, but lost to compatriot Sara Saito.

Professional In July 2024, she and compatriot Naho Sato won the doubles title at the Figueira da Foz International Ladies Open. The following month, she made her WTA Tour debut after qualifying for Tennis in the Land, but lost to third seed Kateřina Siniaková in three sets. In October 2024, she qualified for her second main draw at the Toray Pan Pacific Open with a defeat over top qualifying seed Clara Tauson. She then recorded her first WTA Tour wins over compatriot and lucky loser Sara Saito and qualifier Zeynep Sönmez to reach her first WTA 500-level quarterfinal. Ishii withdrew with an abdominal injury before her last eight match with sixth seed Diana Shnaider. As a result, she reached a career-high ranking of No. 203 on 28 October 2024.

In March 2025, she received a wildcard into the main draw of the Miami Open, but lost in the first round to Emma Raducanu.

Performance timelines

Only main-draw results in WTA Tour, Grand Slam tournaments, Billie Jean King Cup, United Cup, Hopman Cup and Olympic Games are included in win–loss records.

Singles Current through the 2025 Miami Open.

ITF Circuit finals Singles: 3 (1 title, 2 runner–ups) LegendW25/35 tournaments (1–1)W15 tournaments (0–1)Finals by surfaceHard (1–2)

Doubles: 2 (1 title, 1 runner-up) LegendW100 tournaments (1–0)W35 tournaments (0–1)Finals by surfaceHard (1–1)