SHENZHEN, China - Raemon Sluiter has announced the end of his four-year coaching partnership with World No.10 Kiki Bertens today.

"I would like to thank Kiki for her trust, hard work and dedication over the last four years," the Dutchman posted on social media. "I wish her, Remko and Elise all the best for the future. I would like to thank the WTA and all my fellow coaches. Life on tour can be tough, but I really had the feeling that we were in the same boat."

Bertens followed Sluiter's post up with a statement of her own: "Sometimes you also have to make tough decisions which you believe it would make you better," she wrote. "Next year I will not continue to work with Raemon anymore. I would like to say thank you for everything you have done for me in the past 4 years. I have grown as a player and as a person. Without you this would have been impossible. Thank you for everything! Next year I will continue to work with Elise [Tamaela] as my coach."

Sluiter, a former ATP World No.46, began working with Bertens in August 2015, when the Dutchwoman was ranked World No.110. The following year, she rocketed up the rankings to finish 2016 as World No.22 after winning her second career title in Nurnberg and making her first Grand Slam semifinal at Roland Garros - and over the next three years, the 27-year-old would embed herself at the top of the game, gradually translating her formidable claycourt game to other surfaces. The past 13 months have seen Bertens pick up the two biggest titles of her career at Cincinnati 2018 and Madrid this year, make consecutive appearances at the WTA Finals and hit a career-high ranking of World No.4 in May.

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Those results from Bertens followed a warning Sluiter issued at the 2017 WTA Finals, where she competed in doubles, that he would leave her team unless she changed her approach to get the most out of her career.

This year, Sluiter did not travel to Shenzhen with Bertens, who made it into the draw as an alternate and scored a win over World No.1 Ashleigh Barty before retiring against Belinda Bencic due to a viral illness. Instead, she was accompanied by Elise Tamaela in the coaching role.