Kei Nishikori splits with longtime coach Dante Bottini

Kei Nishikori splits with longtime coach Dante Bottini

The world No. 9 hasn't played since the US Open due to an arm injury.

Kei Nishikori has decided to stop working with coach Dante Bottini, announcing the move on social media.

Nishikori began working with Bottini, a coach at the IMG Academy where the Japanese trains, in 2010. The 29-year-old also added Michael Chang as a coach in 2014, when he also reached his first Grand Slam final at the US Open.

Nishikori did not announce any changes in his partnership with Chang.

He has been sidelined with an arm injury not played since the US Open, withdrawing from his home event at Tokyo, the Shanghai Masters and this week's scheduled meeting with Roger Federer in a Tokyo exhibition.

Nishikori is next scheduled to play the Masters event at Paris.