Nick Kyrgios' mother believes her son would be "upset a lot" by stinging criticism of his on-court antics, but asked for patience as he learns the fine line between passion and respect as he grows up in the public eye.

The 20-year-old's behaviour has come under fire after he declared in a pre-Wimbledon interview "I don't really like the sport of tennis that much".

He also threatened not to play when he copped an incorrect call by chair umpire Mohammed Layhani during his first round win over Diego Schwartzman on Monday.

The world No.29 was picked up uttering "dirty scum" by on-court microphones, and later denied it was directed at Layhani but at himself.

Nill supports her son standing up for himself, but said he was still maturing and learning how to express his emotions the right way.

"I think it [criticism] would upset him a lot," Nill said. "Even though the official has admitted yes, he [Kyrgios] was right, the way he went about it was maybe not the way he should have.

"But it was heat of the moment, he wanted the correct decision.

"He needs time to work out exactly how to approach these things, but good on him for standing his ground. [He needs to] approach it with a little more respect. Nick's learning that.

"You have to learn from experience; you can't make people learn things, they've got to learn yourself.

"People are saying he doesn't care [about tennis]. Of course he bloody cares. He wouldn't put himself in that position if he didn't care.

"John [Morris, manager] would have spoken to him for sure. There's nothing you can do [about umpire calls]; control what you can control and do your best. You can't control someone else's call, why worry about it?"

Asked if the negative feedback of his behaviour upset her, Nill said: "Yeah, definitely it upsets me. It really does.

"People need to think about when they were 20 and all the things they did themselves that may not be right, but people don't care because they're not in the public eye.

"They don't get scrutinised. When I was 20 I was doing some mad things myself.

"Only a minority of people really know what it feels like when you're out there doing your job, and you expect everybody to know the rules.

"On court the littlest  thing you say is picked up by the microphone now. You can't even say boo. If you're playing sport who doesn't swear? It's not a good thing but something to release a bit of pressure."

Nill said she became infuriated when criticism of her son was out of context.

Kyrgios was panned for yelling "Oi! Where are you going?" when three spectators tried to leave his Australian Open match against Andreas Seppi early in January.

"Everybody's got an opinion, but sometimes you've got to know the fully story," she said. "The opponent [Seppi] was just about to serve, and those people moved. Where's the etiquette in that? Nick was ready to return.

"It annoys me when people say he's so cocky people can't leave his matches."

Australian tennis has always demanded its players be competitive, but also respectful at the same time.

Pat Rafter has a cleanskin image but Nill revealed the two-time US Open champion also felt the need to release some frustration on court.

"Pat said [to Kyrgios] maybe you should go and train somewhere where no one's watching," Nill said.

"He said when I trained out the back somewhere where nobody could find me, I used to smash my racquets and didn't care, because nobody knows.

"Twenty isn't all that mature for a guy, you're still experimenting."