Nick Kyrgios has dragged tennis into the gutter with his Wimbledon antics, according to Pat Cash.
According to Kyrgios' compatriot Cash, the Australian has taken the sport "to the lowest level" with his on-court behaviour in the first week of the tournament.
The 27-year-old beat fourth seed Stefanos Tsitsipas 6-7 (2-7) 6-4 6-3 7-6 (9-7) in an enthralling round-three tie on Saturday.
Tsitsipas accused his opponent of "constant bullying" after the ill-tempered clash, which was followed by a riposte as Kyrgios said the beaten Greek was "soft" and denied being a bully.
Kyrgios frustrated Tsitsipas by calling for him to be defaulted after the world number five narrowly missed a spectator when firing a ball into the crowd at the end of the second set.
The umpire was then labelled a "disgrace" during an extraordinary Kyrgios outburst, and his behaviour seemed to get under the skin of Tsitsipas, who was deducted a point for sending another ball towards the spectators before appearing to hit a couple of shots directly at his opponent's body.
Kyrgios has been a repeated critic of umpires and line judges, often appearing to show contempt to authority figures, and Cash – Wimbledon champion in 1987 – has had enough, calling out his countryman's conduct.
Speaking on BBC Radio 5 Live, Cash said: "It was absolute mayhem. He's brought tennis to the lowest level I can see, as far as gamesmanship, cheating, manipulation, abuse, aggressive behaviour to umpires, to linesmen.
"He was lucky to even get through the first set, he should have been defaulted in about the first set. Something's got to be done about it. It's an absolute circus.
"Is it entertaining? Yeah, possibly. But it's gone to its absolute limit now."
Asked how he considered Kyrgios to be cheating, Cash said: "The gamesmanship, the stuff that he was doing. The abuse that he was giving Tsitsipas.
"Tsitsipas would make a line call and he'd go up there and he'd start complaining, he was in his face. That's a part of gamesmanship. That's the sort of stuff that he does and I think there's a limit."
Cash's criticism comes ahead of Kyrgios facing American Brandon Nakashima on Monday. That match has been given the prize billing of first up on Centre Court, despite neither man being seeded.
The tennis authorities may not approve of some of the behaviour, but they know there is a huge public fascination with the highly talented Kyrgios, which is why that match has such a prestigious slot. He is 40th in the ATP rankings, and 20-year-old Nakashima is 56th on the list.
Kyrgios is just one win away from matching his best run at Wimbledon, having reached the quarter-finals in 2014 with a win over Rafael Nadal before being beaten by Milos Raonic.
Yet Cash indicated the loudmouthed showman should face sanctions for his actions.
"I have no problem with a bit of gamesmanship, but when it gets to that level I think it's out of control, and it was," Cash said.
"The umpire had lost control, the ball kids were running across the court as Kyrgios was serving. He didn't slow down for any of that stuff.
"Tsitsipas got sucked right in, so it was entertaining, and it was fascinating, but for me it's gone too far now."