Nick Kyrgios has dismissed suggestions that he should apologise to Rafa Nadal for deliberately attempting to smash the ball at the Spaniard's chest in the third set of their feisty second-round encounter at Wimbledon.

Nadal went on to win an epic encounter 6-3, 3-6, 7-6, 7-6 and the world number two branded his Australian opponent "dangerous" after the match.

"The history of this sport is about respect and is about playing fair during the whole time.

"I don't say Nick does this stuff to bother the opponent, but it is true that sometimes he's dangerous.

"When he hits the ball like this, is dangerous. It is not dangerous for me, it is dangerous for a line referee, dangerous for a crowd. When you hit the ball like this, you don't know where the ball goes.

"I know he's a big talented player, but I am a professional player too. I know when you hit this kind of ball, the ball can go anywhere.

"This time the ball went in, almost hit me, no problem. I am professional, so I know how to avoid this. But another one, the ball goes straight to the back. So (it would) have been a dangerous moment for the line umpire.

"That ball hits an eye or something like this, is a problem. That's it. Is not about that I am angry about him at all. It's about I want to play a match of tennis. Sometimes it is difficult."

But Kyrgios feels his opponent is experienced enough to deal with rough treatment.

"Why would I apologise?" Kyrgios said. "I didn't hit him. Hit his racket, no? Why would I apologise? I won the point.

"I don't care. Why would I apologise? I mean, the dude has got how many slams, how much money in the bank account? I think he can take a ball to the chest. I'm not going to apologise to him at all.

"I was going for him. I wanted to hit him square in the chest. Like, he's got decent hands."