Nick Kyrgios' recent display against Pierre-Hugues Herbert in the US Open pretty much epitomises why figures in the world of tennis have been frustrated by the Australian's rollercoaster career.

Against Herbert, Kyrgios got off to a disappointing start, losing the opening set and trailing by a break in the second.

The Australian seemed destined to be tumbling out of the competition - that was until umpire Mohamed Lahyani stepped in.

Lahyani was seen giving Kyrgios a 'pep talk', saying: "I want to help you, I know this is not you." 

Kyrgios went on to win the match 4-6, 7-6, 6-3, 6-0, which caused Herbert to heavily criticise the umpire's actions.

Many players have chimed in on the matter, the latest of which is 13-time Grand Slam singles champion Novak Djokovic, who eased through to the next round after a four-set win over Tennys Sandgren.

Djokovic insisted that Lahyani has a very distinct style of officiating and was only acting in Kyrgios' best interests.

He said: "I heard a little bit about it, but I haven't seen it to be honest. 

"Mohamed, whether he came down from the chair or not, he tried to encourage him to play better, to remind him that he has a responsibility towards the fans. I understand why people are upset over what happened. A chair umpire should be neutral.

"But everybody who knows Mohamed knows as well he's quite different from the others. He's always very positive, smiles, tries to bring that energy to the court. He likes to make a show, as well, out of it.

"Knowing Mohamed, I really don't think that he meant to do it for any other reason but to help Nick understand that if he continues doing that, he might get a fine or penalty or whatever."

Kyrgios has since defended Lahyani's actions, claiming he didn't receive any coaching from the umpire at all.

He said: "It's ridiculous. I don't have a coach and haven't had one for years, of course he wasn't coaching me.

"I'm not sure it was encouragement. He said he liked me, I'm not sure if that was encouragement. He just said that it wasn't a good look."

Kyrgios will next take on world number two Roger Federer in the third round of the US Open.