Tennis great John McEnroe labelled Kyrgios a “black eye for the sport” after the volatile star inexplicably blew a two-set advantage to fall 1-6 6-7 (1-7) 6-4 6-1 10-8 to Italian Andreas Seppi last night.

The 21-year-old carried a knee injury into the tournament and engaged in a running verbal battle with his courtside box over what he later dubbed “poor management” of his “banged up” body.

Obviously I wasn’t physically 100 per cent… but it’s mental

But while accepting he wasn’t physically strong enough for his home slam after hurting himself playing basketball earlier this summer, Kyrgios said his biggest problems were psychological.

“It’s mental. Mental side of things are big for me,” he said.

“That’s where a coach would be good … I don’t think there’s anyone in the top 100 without a coach except for me. That needs to change.

“Got to start taking it more seriously. Pre-season is an important part of the year. You build foundations for the rest of the year. Yeah, it’s on me.

“Obviously I wasn’t physically 100 per cent. But it’s mental.”

Kyrgios received an eight-week suspension for tanking at the Shanghai Masters in October, reduced to three weeks on the condition that he consulted a psychologist.

He said he was continuing the counselling and that it was “going very well”.

But when asked if the psychologist was in Melbourne, the world No.13 sarcastically said: “Johnny Mack [McEnroe] will know, mate. Just talk to him. He knows everything.”

Kyrgios had been in command before his mid-match meltdown.

He stood two games away from winning a place in the third round at 4-4 in the third set when, after constantly bickering towards his entourage, he was broken for the first time.

Kyrgios was docked a rare penalty point after receiving a second code violation for smashing his racquet into the court on the ensuing changeover, before Seppi served out the set to gain a foothold in the match.

He dropped serve twice more as Seppi raced through the fourth set to force a decider – two years after Kyrgios denied the Italian 8-6 in the fifth on the same court at Melbourne Park.

Kyrgios re-engaged to again close to within five points of victory with Seppi serving at 3-4 and love-40 in the tense deciding set.

Seppi – who took out Roger Federer in the third round in 2015 – saved all three break points, including the first with a lucky net cord, before wriggling free to hold.

He broke Kyrgios the very next game but, staring down the barrel, the Australian broke straight back after an audacious between-the-legs shot to send the capacity crowd inside Hisense Arena into raptures.

He garnered a match point in the 17th game of the crazy final set, but Seppi rifled a fearless forehand winner down the line to stay alive, before breaking Kyrgios and closing out the rollercoaster affair after three hours and nine minutes.

Watching on from the Seven Network bunker, Australian Davis Cup captain Lleyton Hewitt hoped his charge could turn the contest around.

“He plays his best tennis when he’s happy, in that happy place. For some reason, he’s not now. He’s struggling,” Hewitt said.

Fellow former world No.1 Jim Courier described Kyrgios’s antics as “apathetic”.

“He seems to be making a specific point to someone in his team that they messed up,” Courier said.

“At one point, does he re-engage?”

Struggling to digest his demoralising defeat, Kyrgios said he was likely to pull out of the Open doubles with Brit Dan Evans and that it was “far too soon” to think about Australia’s Davis Cup tie against the Czech Republic next month in Melbourne.

“I hope I can play, though,” he said.

“I love playing for Rusty (Australian captain Lleyton Hewitt). He’s always been there for me. Hopefully I can play, but we’ll see.

“There’s a lot of good players at the moment who can fill in for my spot and maybe do a better job.”

Seven-time grand slam champion McEnroe lashed Kyrgios, labelling his apparent lack of effort mid-match as “black eye for the sport”.

“You know my history and career and all – I’m someone who’s emotional and goes too far at times and says the wrong things,” McEnroe said during commentary for Eurosport.

“What I don’t understand, and don’t accept, and can’t accept is when he starts going into the tank and he stops trying and giving 100 per cent.

“When he goes through those periods where he’s not competing, that’s just a black eye for the sport and a black eye for him.”

Kyrgios made light of McEnroe’s criticism at his post-match press conference, saying his “body was sore”.

The comments by American, however, got under the 21-year-old’s skin.

When asked about whether he had a sharp pain in his knee, Kyrgios responded: “I don’t know, mate. Ask Johnny Mac.”

And whether he was consulting a sports psychologist in person in Melbourne or on the phone: “Johnny Mac will know, mate. Just talk to him. He knows everything.”

McEnroe said Kyrgios could be the best in the world if he got his mental game together.

“I would call it a damn shame because I think he’s the most talented guy in the world 21 and under – maybe even at 29 and under.

“He could be the best player in the world, but mentally he’s number 200 in the world and I think at critical moments it showed.”

Fellow trouble-prone young gun Bernard Tomic says all players, including Kyrgios, need a team on their side to get to the top in tennis.

World No.27 Tomic, who advanced to the third round with a tough four-set win over Victor Estrella Burgos, said he wouldn’t be where he was without his dad John.

You can’t do this on your own, you need a good team of people

Tomic senior doesn’t travel full-time with his son anymore but still guides his career.

“I wouldn’t say I’m coach free, I still have my dad who is there helping me, as a coach, as a father,” 24-year-old Tomic said.

“He’s not travelling much as well, because he’s with my sister, but of course, there needs to be people helping you, wanting to achieve things.

“You can’t do this on your own, you need a good team of people around yourself.”

-AAP