Maria Sharapova has parted ways with longtime coach Sven Groeneveld. The Russian released a statement on her website today, officially ending a partnership that begin late in 2013.

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“After four successful and challenging years of collaboration together, I would like to thank Sven for his incredible loyalty, work ethic and most importantly the friendship that we have formed that will go beyond this working partnership,” Sharapova wrote. “Although we have mutually agreed to part ways during this time, I have been incredibly fortunate to have a team leader like him in my corner for the past four years.”

Since returning from her 15-month doping ban, Sharapova has struggled to find her best form. She has gone 21-10 since returning to the tour last spring, with a title in Tianjin and three semifinals in total. Sharapova has played two majors, going 5-2 and reaching the second week at this year’s Australian Open.

But she has had difficulty getting healthy and has only played once since the Australian Open.

Groeneveld waited for Sharapova to return rather than taking another job, but sadly he won’t be the one to see the Russian back to the top of the sport—if it happens.

“Maria has been one of the most hardworking and professional players I have ever worked with,” he said in a statement. “Her strength and fighting spirit will continue to be a force to reckon with and I have the deepest respect for her as a player and person.”