Nick Kyrgios has responded angrily to John McEnroe’s claim that he “stopped trying” during his Australian Open second round defeat to Italian Andreas Seppi.

The Australian was booed off by his home crowd after going down in five sets against a man 139 places below him in the world rankings on Wednesday.

During commentary, McEnroe – himself a seven-time grand slam winner – accused Kyrgios of letting down the sport.

“What I don't understand, what I can't accept, is when he stops trying. It's a black eye for the sport,” McEnroe said as he watched the number 14 seed blow a two set lead and a match point while appearing to show little interest in chasing the ball down.

When told about McEnroe’s comments in a press conference after the game, Kyrgios hit back and blamed injury for the defeat instead.

“Well, my body was sore. I was hurting. I mean, John McEnroe, was it John McEnroe? Good on him. Great career. Good on him,” Kyrgios said.

When asked if he had felt pain in his knee, referencing a long-standing injury problem, Kyrgios replied: "I don’t know, mate. Ask Johnny Mac. He knows everything.”

Kyrgios, who is currently without a head coach, was seen speaking to his team in the stands during the game, complaining about his conditioning. When pressed on what he was talking to them about, he responded:

“Poor management, I guess,” he explained. “I think I didn't have the best preparation. It's on me. Did a couple things in the off-season that I'm probably not going to do next time. It's on me, I guess. My body's not in good enough shape. You live and you learn.

When asked exactly what he would do differently in preparation, Kyrgios went on to blame his injury on playing too much basketball.

“I don't know, maybe just not play as much basketball. Actually take my pre-season seriously. It was fun. I love to play. Hurt my knee.”

Kyrgios, who admitted it was “not the greatest” to be booed off the Rod Laver court, also blamed part of his defeat on psychology.

“I think it’s mental. Mental side of things are big for me. That’s where a coach would be good. But obviously I wasn’t physically 100 per cent. But it’s mental as well. A massive part of it.”