Roberto Mancini has accused Mario Balotelli of risking his career by refusing to adopt a professional attitude to life at Manchester City.
It has been alleged that Balotelli's car was surrounded by Manchester United fans as he tried to leave the Etihad Stadium following Sunday's 3-2 defeat to the Red Devils.
Although the Italy striker was not threatened, it was not the only time he was abused by supporters, only earlier it had been his own fans attacking him for making his way straight down the tunnel after he had been replaced by Carlos Tevez.
And after another tepid performance in a largely disappointing campaign, Mancini has warned the 22-year-old time is running out for him to start accepting the responsibilities that come with his status.
"I love Mario but it is important for him to start to think about his job," the City boss said.
"He has everything to play well but he can't continue to play like today. We wanted more from him.
"When you have a player that has Mario's quality, you cannot understand why he continues to throw it out of the window. It is incredible.
"I have seen players in my life with fantastic quality. But in the end, they did nothing. I don't want Mario to finish like these players. It would be bad for him."
That Tevez helped turn yesterday's game on its head until Robin van Persie's injury-time winner just underlined Balotelli's negligible contribution.
He did set up Sergio Aguero with one fine through ball, but it was not until after Tevez's arrival that Yaya Toure and Pablo Zabaleta grabbed the goals that hauled City level and, briefly, threatened victory.
Instead, the Blues find themselves six points adrift of their neighbours after their 37-match unbeaten home record in the Premier League was blown apart by Van Persie's deflected free-kick.
Nevertheless, despite the spectre of Pep Guardiola continuing to hang over him after an awful week in which his side bowed out of all European competition on the back of the worst English performance in Champions League history, Mancini insists City can still retain the title.
"Even though we have lost this game we have shown we can win the title this year," he said.
"It is clear, we need to work hard and stop making mistakes. We can't continue to go one or two goals behind because it is difficult to recover.
"We have a good spirit. Now we need to win four or five matches in a row."