Nick Kyrgios was the recipient of lenient treatment from the chair umpire during his feisty Wimbledon clash with Stefanos Tsitsipas, so says John Lloyd.

Kyrgios has caused a stir at The All England Club over the past week, making headlines not only for his high-quality tennis, but his on-court behaviour.

The outspoken Australian is no stranger to arguing with umpires and line judges but has been particularly vitriolic at times at Wimbledon.

On Saturday he clashed with Tsitsipas, who subsequently accused the 27-year-old of being a "bully". Both players were fined for their conduct.

Now into the quarter-finals after beating Brandon Nakashima on Monday, Kyrgios has matched his best run at a grand slam, reaching the last eight at a major for the first time since 2015.

But former British number one Lloyd believes that stern calls from umpires are the way to keep a lid on Kyrgios' emotions.

Lloyd told Stats Perform: "I love watching Kyrgios because he is in some ways, it's almost like a [Roger] Federer, not in the personality, but the way he can conjure up shots that no one else can get.

"And plus, you never know what he's going to do with the drop, the underarm serves and various other things. That makes him a fun guy to watch. The game is looking for characters and I think we always say that [about Kyrgios].

"I have no problem with some of the stuff he does. But when it gets to the stage, which it was on Saturday, when it becomes a circus where it's all about him, there has to be a line there. 

"I think what happened was the umpire messed up. Something I can't understand is when you're umpiring Nick Kyrgios in a match as big as this, you have to put the best guy out there that won't stand for any stuff. In other words, you've got to set the standard from the beginning.

"[A line judge] came up to the umpire after the second or third game in the middle of the rally to say basically that he had sworn and the umpire sort of looked and then hesitated, didn't give him a warning. It was almost like he was thinking, 'I'll let this one slip.'

"Well, with certain players, you could let it slip. But with Nick, he should have come right down on him. So he should put out the setting to say this is not going to happen and he didn't do that, and after that, Nick just got all over him."

Lloyd also feels that world number five Tsitsipas, who was defeated 6-7 (2-7) 6-4 6-3 7-6 (9-7) allowed Kyrgios to get under his skin.

"Tsitsipas was the sideshow. He's just trying to play tennis, and he's not being allowed to because of the constant barrage of talking going on," Lloyd added.

"He's rushing him the whole time. That's Tsitsipas' fault in some ways. He could have slowed it down. He was trying to be professional.

"When he lost the second set, he exploded. Hit the ball into the crowd, it did hit someone off a rebound. He could have got defaulted there.

"But for me, it was Kyrgios that goaded him for the first couple of sets and he was allowed to basically control the way the match was going, and I think that's got to be stopped. It's okay to have a bit of entertainment here and there, but not to the stage where your opponent can't play properly because of all the stuff that's going on."

Kyrgios will face Cristian Garin for a place in the semi-finals. It will be the first quarter-final between two unseeded players at Wimbledon since Arnaud Clement took on Rainer Schuttler in 2008.