Different - it's how Thanasi Kokkinakis and Lleyton Hewitt described fellow Australian tennis star Nick Kyrgios.

"A different cat," Kokkinakis says about his close friend who he grew up with through the ranks of Australian tennis.

Those closest to the 20-year-old, who lines up against Canadian Milos Raonic in the third round of Wimbledon on Friday, have been defending him.

They know that's just who he is.

However, the Australian public have turned, and different isn't how they are phrasing it.

Some have called Kyrgios disrespectful, others say he is arrogant.

He has had altercations with two separate umpires already in the first two rounds, but Kokkinakis, who was sitting courtside for his second outburst, is no stranger to the roadshow that is 'NK Rising', admitting he enjoyed watching the No.26 go about his business the way he does.

"I'm used to it. It's always a circus when Nick hits the court," Kokkinakis said.

"I like watching it because I don't know what'll happen next. So I think it was 1-all in the first set, he was down 40-love on [Juan] Monaco's serve and he saw me - I was late to get in after having a hit with Rusty - he gives me a wink and he smiles at me.

"He's just a different cat, but I find it funny to watch ... I see it a little bit differently. Obviously he does say some stuff which a few people take as a bit disrespectful. But I've known him for so long, so i'm kind of used to everything that he's doing and the way he acts so it's nothing too new to me."

Hewitt was coy about the antics of Kyrgios, despite Australia's No.1 male tennis player being likened to a younger version of Hewitt.

While he admitted he was 'different', Hewitt was reluctant to open up about his thoughts on Kyrgios while he was still playing in the tournament.

"I wouldn't speak about it now anyway," Hewitt said.

"I got to know him a lot better when we played the Asian League at the end of last year together and we got to play some doubles sets together and we spent a lot of time travelling there. As Thanasi said, he's a different guy but the biggest thing about the three young guys that we have now is that they all handle pressure and expectation differently.

"But they all thrive on getting out there on the big courts and playing well under pressure and since me, the next batch of guys would really struggle with those guys that would go out and handle that. But these three guys can. So as much as Nick is different and he does things his way, but he is still able to get the result most of the time."