Osaka's time with Mouratologou followed an up-and-down sequence of promising signs and frustrations with either injury or close-run defeats.

Osaka, a four-time Grand Slam champion, has been in a career rut for years. Mouratoglou joined her staff in September of 2024 and there hasn't been much improvement. Osaka has not made it past the third round of a Grand Slam tournament since 2021 when she won the Australian Open. Now she will look for a new coach to help bring her back to form.

The news comes after Naomi Osaka lost her second match at the D.C. Open and just before she begins competing in Toronto.