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

So far, the early results are promising for the budding partnership between Osaka and Wiktorowski. Osaka defeated Ariana Arseneault in the first round of the WTA 1000 Montreal yesterday. However, Osaka will face much stiffer competition in the 13-seed Liudmila Samsonova tomorrow. Currently, Osaka is the World No. 49 with a record of 22-11.

Naomi Osaka's coaching experiment with Tomasz Wiktorowski is already showing promise. The four-time Grand Slam champion began her new partnership this week at