Four-time Grand Slam champion Naomi Osaka has split with coach Patrick Mouratoglou after just shy of a year together.

Osaka confirmed the split on social media ahead of the WTA 1,000 Canadian Open in Montreal, as the tennis shifts to hard courts, where she is most comfortable.

“Merci Patrick. It was such a great experience learning from you. Wishing you nothing but the best. You are one of the coolest people I’ve ever met and I’m sure I’ll see you around,” she wrote in a statement.

Mouratoglou did not immediately respond to a request for comment.

Osaka, 27, started working with Mouratoglou, who most famously coached Serena Williams, following the 2024 U.S. Open. Their time together has been an up-and-down sequence of promising signs and frustrations with either injury or close-run defeats for Osaka, who said that Mouratoglou would be left wondering “what the f— this is ” after a tight first-round loss to Paula Badosa at this year’s French Open.

Ahead of that tournament, Osaka played a second-tier tournament in Saint Malo, France, after an early loss at the Italian Open in Rome. She won the WTA 125 event in France. reflecting afterward how missing matches due to physical issues — and three frustrating retirements with injury during promising contests in Beijing, Auckland and Melbourne in late 2024 and early 2025 — had left her lacking reps in tight moments.

But at the French Open against Badosa, and then at Wimbledon against Anastasia Pavlyuchenkova, Osaka went through the kind of encouraging but ultimately dispiriting match that has marked much of her time with Mouratoglou. Prior to a 6-4, 6-2 defeat to Emma Raducanu at the D.C. Open that proved to be their last match together, six of Osaka’s last seven matches had come in three sets, with all of the deciders ending 6-4 against or in a tiebreak.

Following the defeat to Pavlyuchenkova, Osaka said that her response to it was entirely removed from her emotions in Paris, where she had to briefly leave the interview room in tears.

“In Paris, I was very emotional. Now I don’t feel anything, so I guess I’d prefer to feel nothing than everything,” she said in London.

Osaka, who is currently world No. 51, will play Canadian qualifier Ariana Arseneault Monday in her first match at the Canadian Open.

(Photo: David Gray / AFP via Getty Images)