Alexander Zverev has said he found it very hard to lose coach David Ferrer earlier this year because they were such a good match.
Ferrer became part of Zverev's coaching team in July 2020 and in their brief spell together it appeared to be a successful pairing.
During the partnership the World number seven reached the final of the US Open for the first time, the final of the Paris Masters and he won two consecutive ATP 250 Titles in Cologne.
But following the ATP Finals in London, Zverev says he received a call from Ferrer with disappointing news.
"I didn't want to part with him. We said that we had to talk to each other after London and observe the world situation," Zverev told Eurosport Germany.
"He then called me and said it was difficult because he wants to be with his wife and son.
"When he goes to tournaments with me, he has to go into two-week quarantine every time afterwards and can't spend the time with his family.
"That was hard for me because I didn't want to let him go.
"I loved him as a trainer. For me he was the best coach, apart from my father. I have to accept that, of course.
"We were an incredible match in terms of personality, the way we see tennis and coaching.
"The coaching work is not just what you do on the court. It's the personalities that have to fit together."
Zverev recently left his management agency and has confirmed that he will keep his support team much closer to home with his dad and brother looking after both coaching and management.
The German will lead his country in the ATP Cup before competing in the Australian Open starting on 8 February.
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