Naomi Osaka is making a major change at the start of the North American hard-court swing as the former world No. 1 decided to call time on her partnership with coach Patrick Mouratoglou.

Four-time Grand Slam champion Naomi Osaka said Monday that she has split with coach Patrick Mouratoglou after less than a year.

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