Greek fourth seed Stefanos Tsitsipas labelled Nick Kyrgios a "bully" with "an evil side" to his character after losing a bad-tempered Wimbledon third-round clash on Saturday.

Kyrgios kept up a running dialogue with the umpire during the match, was warned for obscenities and upset his opponent to such an extent that Tsitsipas came close to being defaulted for whacking a ball into the crowd.

It was easy to feel sympathy for the 23-year-old Tsitsipas who won the first set 7-6(2) but lost his composure after being caught up in what he described as a Kyrgios circus.

After his stormy 6-7(2) 6-4 6-3 7-6(7) defeat on Court One, Tsitsipas made his feelings known in no uncertain terms.

"Yeah, it's constant bullying, that's what he does. He bullies the opponents. He was probably a bully at school himself. I don't like bullies," Tsitsipas said.

"I don't like people that put other people down. He has some good traits in his character, as well. But he also has a very evil side to him, which if it's exposed, it can really do a lot of harm and bad to the people around him."

Kyrgios, fined $10,000 after his first-round match for spitting towards a fan, was warned for swearing on Saturday and then called for Tsitsipas to be defaulted after the Greek hit a ball close to a spectator's head after losing the second set.

Tsitsipas apologised for losing control but said it was frustrating that the umpires did not come down harder on the Australian.

"I wish we could all come together and put a rule in place. I don't know. Something about talking. Why would you be talking while you're playing? It makes no sense," he said.

"Every single point that I played today I feel like there was something going on on the other side of the net.

"That's his way of manipulating the opponent and making you feel distracted, in a way. There is no other player that does this. There is no other player that is so upset and frustrated all the time with something.

"I really hope all us players can come up with something and make this a cleaner version of our sport, have this kind of behaviour not accepted, not allowed, not tolerated."

Tsitsipas admitted he had tried to hit Kyrgios with a smash in the third set.

"I was aiming for the body of my opponent but I missed by a lot, by a lot," he said. "I'm not used to play this way. But I cannot just sit there, act like a robot and act like someone that is completely cold and ignorant.

"Because you're out there doing your job, and you have noise coming from the other side of the court for no absolute reason."