World No.1 Naomi Osaka has ended her successful partnership with coach Sascha Bajin.
"Hey everyone, I will no longer be working together with Sascha", Osaka wrote. The 21-year-old announced the news on Monday on Twitter.
Under Bajin, Osaka rose from world number 72 at the start of the 2018 to the summit of the rankings little over a year later.
Osaka's agent confirmed to The Associated Press that Osaka would no longer be coached by Bajin but said there would be no further comment.
The Japanese went on to claim her first WTA title of her career at Indian Wells in March, defeating Maria Sharapova, Karolina Pliskova and Simona Halep to achieve the feat.
Adding her third victory to her growing list of honours in January, Osaka credited her team and Bajin, for their part in her rapid rise to Grand Slam success.
Bajin responded: "Thank you Naomi I wish you nothing but the best as well".
"Behind every tennis player is a great team".