Japanese tennis star Naomi Osaka says she has split from her coach, Jermaine Jenkins.
Osaka said on Twitter that the two won't be working together anymore.
She said she was grateful for the time they spent together and the things she learned on and off the court. But she said she felt it was time for a change.
It's the second time this season that the two-time Grand Slam champion has split with a coach.
She terminated her contract with Sascha Bajin soon after winning the Australian Open in January. The pair had worked together for more than a year.
Under Jenkins, Osaka worked on her serves and strokes, but failed to deliver satisfying results. Her advance to the fourth round at the US Open was the best result she got in a Grand Slam event this season.
Sources say Osaka parted ways with the American coach to change her training environment and aim for further improvement. They say she hasn't decided on a replacement.
Osaka is due to compete in a WTA tour event in Osaka City in Japan next week.