Nadal won an epic Wimbledon second-round grudge match against Kyrgios with a 6-3, 3-6, 7-6(5), 7-6(3) victory.
However, the world No 2 was raging after being at 4-4 in the third set when the ball was fizzed at his body.
Kyrgios was just inside the baseline when he let loose with a ferocious forehand which struck Nadal, who had moved into the net.
The 18-time Grand Slam winner stayed in his position as the ball cannoned into net and proceeded to give his opponent a death stare, which he held for a few seconds.
After the match, Kyrgios refused to apologise to his rival and even admitted he did it on purpose.
“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, bro. I’m not going to apologise to him at all.
“Yeah, I was going for him. Yeah, I wanted to hit him square in the chest. Like, he’s got decent hands.”
Nadal refused to complain about being lashed with the ball in his post-match press conference.
But he did feel the effort was dangerous as it could have hit anybody else inside the ground.
“Honestly, is not about what I feel or what I don’t feel,” he said.
“Honestly is about we are in a game that 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 is true that sometimes he’s dangerous. When he hit the ball like this, is dangerous.
“It’s not dangerous for me, 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 have been dangerous moment for the line umpire. That ball hits an eye or something like this, is a problem. That’s it.
“Is not about I am angry about him at all. It’s about I want to play a match of tennis. Sometimes is difficult.”
The bad blood between the pair stems from their brutal clash at the Mexican Open earlier this year.
They have since traded insults in the press and their showdown on Centre Court at Wimbledon was full of fireworks.
Kyrgios continuously attempted to get his opponent into trouble with the umpire for what he perceived to be a slow rate of serving.
And Nadal celebrated like he had won a Grand Slam title when his victory was secured – such is the intensity of their rivalry.