Marian Vajda said it 'felt terrible' to coach a player against Novak Djokovic after they spent so many years together.
All of Djokovic's biggest successes came under the tutelage of Vajda, but they decided to part ways this year.
Vajda has since started working with compatriot Alex Molcan, who Djokovic played in the second round of the French Open this year.
Asked by Tennis Majors what it was like to coach a player against Djokovic, Vajda said: "It was very strange in Paris to be in the opposing box.
"It was a terrible feeling, I have to be honest. I felt so bad, Novak also felt very bad.
"We stay in touch, communicate and send messages to each other. Our relationship is still very good."
Novak Djokovic was certainly in dominant form that day, as he beat the young Slovakian 6-2, 6-3, 7-6.
Vajda, though, has revealed that not only did Djokovic compliment Molcan afterwards, but he even tried to help him.
"[After the match] I sent him a message saying ‘Congratulations’. He played a very good match.
"I told him that Alex is improving, he agreed and told me: ‘He should have attacked my second serve more’. And I was like: ‘My God, you are crazy, you are unbelievable’. He is telling me tactics against himself.
"It was very nice of him to give me some tips on how to improve Alex’s game. He helped me to understand Alex’s game better.
"It is tough to play against Novak and to be in the tournament where Novak is – I always support him and I want him to win Wimbledon."
Vajda is back at Wimbledon again, with Molcan impressing. The 24-year-old has reached the third round, where he will face Taylor Fritz.
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