Nick Kyrgios, outraged about the "jerk" who targeted Novak Djokovic with heckles at the Australian Open, has joked with the Serbian that he would happily have jumped into the crowd to "sort out" his tormentor on Rod Laver Arena.

Djokovic let the heckler get under his skin in the fourth set of his somewhat laboured 6-3, 4-6, 7-6 (7-4), 6-3 victory over Australian Alexei Popyrin on Wednesday night, even ending up marching over towards the seats and challenging the man to "say it to my face".

Genuinely outraged in the commentary box, Kyrgios told Eurosport viewers: "There's always some jerk in the crowd who wouldn't say something to Novak's face.

"There's always going to be people who don't like your success, I guess. It's a shame, because all he does every year is come down here to Australia and give us world-class tennis. Absurd, isn't it?"

Kyrgios noted how Djokovic only seemed to rise to a new level once aggravated by the heckler.

"Hasn't he heard the phrase, 'don't poke the bear'?" Kyrgios said.

Afterwards, Djokovic engaged in a jovial conversation with Kyrgios during an interview.

"Did you like that, Kygs? I invited the guy to come and say it to my face, and he was saying a lot of nice things — and he was apologising from far away," Djokovic said.

"All of a sudden there's an absence of courage when he needs to face me."

Kyrgios responded: "When he was heckling you, Novak, I told everyone from the commentary box worldwide, 'If you want me to jump into the crowd and sort him out, I've got your back 100 per cent, bro.'"

To which Djokovic was left laughing: "I'll keep that in mind — thanks, Kygs."

In a more serious vein, Djokovic admitted it was a difficult atmosphere to play in.

"I was feeling a lot of mixed emotions on the court — not a great atmosphere to play in to be honest," he said.

"People were basically making noise between first and second serve the whole match. Of course, it annoys you but what really frustrates me is when somebody is heckling — so I confront them."

Ultimately, the result was the same as almost all of Djokovic's grand slam encounters with Australian players, as he put paid to a display from Popyrin that Kyrgios felt the Sydneysider should be proud of.

Follow all the Australian Open action via ABC Sport's live blog and Grandstand's live commentary at abc.net.au/sport

AAP