Naomi Osaka has split with her coach Jermaine Jenkins, her second change of coaches this season.

Osaka announced the move on social media, saying she had enjoyed their approximately six-month partnership.

The 21-year-old from Japan has not won a title since the Australian Open, having split with her previous coach, Sascha Baijin, following the event. Having reached No. 1 in the rankings this season, she has since dropped to No. 4, recording four quarterfinals and a semifinal.


Osaka hasn't yet named a new coach.

Another former No. 1, Simona Halep, has announced that Darren Cahill will be rejoining her team next season. The Australian coach helped Halep to get to the top spot and win her first Grand Slam title at the 2018 French Open. Halep, 27, won her second Grand Slam this season at Wimbledon, and is currently No.6 in the rankings.

And Garbine Muguruza has extended her coaching partnership with Spanish Fed Cup captain Anabel Medina Garrigues, who has been helping her since she split with former coach Sam Sumyk following Wimbledon. The former WTA player will also accompany her for the Asian swing, starting next week during Osaka.

The 25-year-old has not won a match since reaching the fourth round of the French Open, and is now No. 27 in the rankings.

Muguruza is a two-time Grand Slam champion.

Osaka drops coach as Halep, Muguruza make team changes

Osaka drops coach as Halep, Muguruza make team changes