John McEnroe accused Nick Kyrgios of giving tennis a bad look as Andy Murray dealt the temperamental youngster another grand slam reality check.
Murray sent the Australian No.1 packing from Wimbledon with a ruthless straight-sets fourth-round win on Monday.
Britain's title favourite dispatched Kyrgios 7-5 6-1 6-4 in less than two hours to end Australia's interest in the singles for another year after Bernard Tomic earlier suffered a disappointing 6-4 4-6 3-6 6-4 10-8 loss to Frenchman Lucas Pouille.
Murray's rout completed a grand slam sweep of wins over Kyrgios after he also removed the Canberran from last year's Australian, French and US Open draws.
While he never expected Kyrgios to conquer the two-time grand slam champion, McEnroe said the way Australia's 15th seed capitulated was a "damn shame".
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"Boy, I expected Murray to win, but not in one hour and 39 minutes," McEnroe said from his courtside commentary box.
"This is not doing our sport any good. What's he's giving, 80 per cent? ... This is Wimbledon, centre court; you've got to give 110 per cent to try to get back into it.
"I tell ya, this is hard to take a whole lot of positives out of this.
"It's not just the mental part, he needs to work on his game.
"He doesn't know what it takes to be a top-10 professional to win grand slams.
"I'm hoping he sees the writing on the wall before this becomes chronic, irreparable, because to me it's getting to that point.
"He's got as lot of thinking to do, a lot of work to do."
McEnroe urged the coachless Kyrgios to appoint a fulltime mentor to help the 21-year-old fulfil his "God-given talents" before his career slipped away.
"I think this would be an important time for his parents to look him the eye and people like Lleyton Hewitt, these are the people who have got to force him to look in the mirror," said the original tennis superbrat.
"It's a damn shame when he does this. It makes no sense whatsoever.
"He's got to take responsibility for what's going on."
There was no telling the much-hyped centre-court showdown would be so one-sided as the pair played cat and mouse for much of the first set as neither was able to make any inroads on their opponent's serve.
Out of the blue, though, Murray conjured three set points after luring Kyrgios to the net before cracking a scorching backhand crosscourt winner to have the Australian down 5-6 and love-40.
Kyrgios saved two of the set points with monster serves, but surrendered the set with a forehand volley into the net.
The miss proved the beginning of the end for Kyrgios as Murray mercilessly raced through the set to take a stranglehold on the match.
"He's not even on the court mentally. He's snapped," McEnroe said.
"It looks like Kyrgios doesn't really want to be out there."
Kyrgios didn't even sit down at the changeover after dropping serve to trail 2-1 in the third set as Murray moved in for the kill.
"It was a good first set," Kyrgios said.
"The rest of the match was pretty pathetic."
HOW THE AUSSIES FARED AT WIMBLEDON (PREFIX DENOTES SEEDING)
Men's singles, fourth round
15-Nick Kyrgios lost to 2-Andy Murray (GBR) 7-5 6-1 6-4
19-Bernard Tomic lost to 32-Lucas Pouille (FRA) 6-4 4-6 3-6 6-4 10-8
