Japan's Naomi Osaka has announced that she has been working with coach Sascha Bajin for more than a year in the past year.
"I will not work with Sascha anymore, I appreciate all his work and wish him the best for the future," he said.
After 13 months of collaboration, the 34-year-old Germans succeeded last year at the Australian Open, winning last year's Indian Wells and US Open. Naomi Osaka is the first in the world.
Sascha Bajin has already worked with Serena Williams for eight years and ended in the spring of 2015. The Germans were accompanied by Belarusian Victoria Azarenka, USA's Sloane Stephens and Denmark's Caroline Wozniacki. He was elected coach of the year by the WTA in 2018.
The Japanese have not played since winning Melbourne, and this week kicked Doha again in Qatar.