Alexander Zverev lost on Thursday night to Daniil Medvedev in which the former served for the match twice but lost 6-3, 5-7, 6-7 at the Monte-Carlo Masters.
But post-match, Zverev accused Medvedev of gamesmanship and cheating by taking a toilet break when supposedly it wasn't possible anymore.
Via Sky and translated by Jannik Schneider, he said: "He is one of the most unfair players in the world. I take fair play and sportsmanship very serious. He does not. He takes a toilet break when it's not possible anymore."
"There are 1000 situations in which he feels that I start to play better and in which he tries to do something every time. I'm extremely disappointed from him as an athlete."
"Of course you can argue that it's not good form from me that I got distracted. This should not happen to me and it's totally my fault and it really was bad from my side. But still I feel fairplay should always be part of sports."