Sofia Costoulas

Sofia Costoulas (; born 2 April 2005) is a Belgian professional tennis player. She has career-high rankings of No. 134 in singles, achieved on 30 March 2026, and No. 229 in doubles, achieved on 25 September 2023.

Early life Costoulas was born in Genk to a Greek-Congolese father and a Belgian mother. Her father was a professional footballer who played for Sint-Truidense V.V., K. Patro Eisden Maasmechelen, and C.S. Visé. She began playing tennis at the age of four. She trained at her local club in Genk, the Kim Clijsters Academy, and the Justine Henin Academy. In September 2021, she reached the girls' singles third round of the US Open.

In January 2022, she won the J1 Traralgon Tennis International, defeating Kayla Cross in the final. In April 2022, she won back-to-back J1 titles in Vrsar and Plovdiv.

Professional In December 2021, she reached back-to-back W15 finals in Monastir. In February 2022, she reached the semifinals of the W25 Copa Banco in Guayaquil.

In April 2025, she won her biggest title to-date at the W75 Ladies Open Calvi Eaux de Zilia, defeating Tessah Andrianjafitrimo in the final. The following month, she reached the second round of the qualifying competition of the French Open, but ultimately failed to advance into the main draw.

Costoulas made her WTA Tour main-draw debut as a qualifier at the 2026 ASB Classic in Auckland and defeated fellow qualifiers Whitney Osuigwe and Kaitlin Quevedo to reach the quarterfinals, at which point her run was ended by third seed Iva Jovic.

Playing alongside Matilde Jorge, she won her first WTA 125 doubles title at the 2026 Oeiras CETO Open, defeating Magali Kempen and Lara Salden in the final.

Grand Slam singles performance timeline

WTA 125 finals Doubles: 1 (title) ResultW–LDateTournamentSurfacePartnerOpponentsScoreWin 1-0 Oeiras CETO Open, Portugal Clay Matilde Jorge Magali Kempen Lara Salden 6–4, 6–2

ITF Circuit finals Singles: 13 (5 titles, 8 runner-ups) LegendW75 tournamentsW50 tournamentsW25/35 tournamentsW15 tournamentsFinals by surfaceHard (4–6)Clay (1–2)

Doubles: 12 (4 titles, 8 runner-ups) LegendW60/75 tournamentsW50 tournamentsW25/35 tournamentsW15 tournamentsFinals by surfaceHard (2–6)Clay (2–1)Carpet (0–1)

Junior Grand Slam tournament finals Girls' singles: 1 (runner-up)

Girls' doubles: 1 (runner-up)