Milos Raonic, Karen Khachanov are the latest to make coaching changes

Milos Raonic has sometimes used three coaches at a time, but is currently working with none.

Longtime advisor Riccardo Piatti announced that he has left Raonic's team, saying, "It's been an amazing ride" but he would now "embrace new adventures and new challenges."

Piatti had been the Canadian's co-coach alongside several high profile names, including Ivan Ljubicic, Carlos Moya, John McEnroe, Richard Krajicek andMark Knowles.

Also, Russian Karen Khachanov has announced he has stopped working with his coach, Galo Blanco—also a former Raonic coach—following a partnership that took him into the Top 50 on the ATP tour. The 21-year-old player said the decision was mutual.

Blanco is still working with another Russian, Andrey Rublev, who trains at his academy.

Neither of the players has announced a replacement.