Japan's Naomi Osaka, a four-time Grand Slam singles champion, will work with Polish coach Tomasz Wiktorowski on a trial basis after splitting with Patrick Mouratoglou after less than a year together.

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

Naomi Osaka surprised a day ago by announcing the end of her coaching partnership with Patrick Mouratoglou after 10 months of working together. The four-time Grand Slam champion had not made the leap she expected with the French coach by her side,