Tokyo, Sep 13 (IANS): Japanese tennis player Naomi Osaka has announced that she will no longer be working with coach Jermaine Jenkins, who joined her team in late February.

"I'm super grateful for the time we spent together and the things I learned on and off the court but I feel like now is (an) appropriate time for a change," the world No. 4 tweeted on Thursday.

Jenkins, 34, was hired after the Japanese star abruptly split with coach Sascha Bajin just weeks after winning her second consecutive Grand Slam at the Australian Open and becoming world No. 1, reports Xinhua news agency.

However, the 21-year-old has not reached the final of a tournament since she hired Jenkins, a former hitting partner for Venus Williams, as well as the US Tennis Association national coach for women's tennis.

In her first attempted title defence, at the US Open in New York in September, Osaka was knocked out in the round of 16 by Belinda Bencic of Switzerland.

Osaka also made a third-round exit at the French Open, before losing in the first round at Wimbledon in July.