John McEnroe, tennis's original superbrat, has warned Nick Kyrgios he risks being "railroaded out of town if he doesn't watch out".
McEnroe is one of Kyrgios's biggest allies and last week invited the embattled youngster to his pre-US Open charity event.
But as Kyrgios arrived for Monday's US Open start to a hostile reception from the New York press, McEnroe expressed fears the 20-year-old's on-court conduct was not only losing the locker room but also affecting his tennis. "He could be incredibly positive for our sport," McEnroe was quoted in the New York Times.
"He's got a chance to be top five, win grand slams. But he's rubbed people the wrong way and he's going to get railroaded out of town if he doesn't watch out."
After reports that 14-times grand slam winner Rafael Nadal refused to play doubles with Kyrgios at McEnroe's event last Wednesday, following the Australian's infamous sledging of French Open champion Stan Wawrinka, Kyrgios dismissed the controversy.
"It's over now," Kyrgios said.
"Everyone's moved on from it, and I'm playing really good tennis. It's part of the journey.
"I don't think anyone was perfect when they were 20. It wasn't the best thing. But I learned from that and keep maturing every day."
McEnroe, though, remains concerned.
"I worry that this is going to take away from what he needs to be doing, which is learning from losses, training hard, learning how to gauge matches mentally, all the things you need to learn to become a grand slam champion, McEnroe said.
"I'm telling you, there's something about this guy. He's a natural, real charisma. That's why I invited him, because I want to be supportive.
"I don't want him to go down that black hole."
The New York Post gleefully greeted news of Kyrgios's daunting first-round confrontation with 2013 Flushing Meadows champion and third seed Andy Murray with the headline: "Kyrgios gets what's coming to him with impossible draw".
"Karma is a killer and tennis's new bad boy Nick Kyrgios got banged in Thursday's US Open draw," wrote Marc Berman in the New York Post's accompanying story.
The New York Daily News' Filip Bondy predicted Kyrgios's Open campaign would be short-lived.
"Don't blink, or get stuck in traffic, because bad boy Nick Kyrgios may not be around for long to rock the US Open," he wrote.
In an earlier Daily News column, Bondy wrote that Kyrgios could not afford one false move at the Open, due to his suspended ban and the brewing ill-will of fellow players.
"He's become something of a pariah on tour, and now one false move and the guy is toast," Bundy wrote.
"Can he hold it together, or will Nick Kyrgios misbehave himself right out of the sport?"
But writing for ESPN, Johnette Howard said Kyrgios's conduct was nothing compared to how the likes of McEnroe and fellow former world No.1s Jimmy Connors, Ilie Nastase and racquet-smashing Marat Safin used to steam and behave.
"The antics that landed Kyrgios in the headlines the past few months were loutish, all right," Howard wrote.
"But for now, he doesn't begin to eclipse even a chronic journeyman crank like Jeff Tarango, whose decision to walk off the court at Wimbledon was a first in the tournament's 109-year history."