Manchester City's open-top bus tour to celebrate their thrilling Premier League victory was marred by Carlos Tevez's displaying of a highly provocative banner aimed at Manchester United manager Sir Alex Ferguson.
"RIP Fergie" was the offending banner, and it has led to Tevez's club being forced to issue an apology to United's manager on a day of celebration.
A City spokeswoman said: "The creation of the tasteless material is in itself reprehensible and in accepting and brandishing it, Carlos has made a significant error of judgement.
"The club wishes to express its sincerest apologies to Sir Alex Ferguson and Manchester United Football Club for any offence or distress caused."
Tevez said: "I got carried away in the excitement of the moment and I certainly didn't mean any disrespect to Sir Alex Ferguson, who I admire as a man and a manager."
It is unclear where he obtained the banner but he did not have it when he boarded the bus to begin the tour of the centre at Albert Square.
The meaning behind it could well be in reference to Ferguson`s famous response to a 2009 question as to whether or not United would ever be underdogs against City. "Not in my lifetime," the Scot said.
City were celebrating their first league title in 44 years after a dramatic last-gasp 3-2 victory over 10-man QPR at the Etihad Stadium on Sunday.
Members of the victorious squad were invited to a private reception at Manchester town hall in the afternoon before taking to a stage to greet a huge crowd in the city's Albert Square.
Mario Balotelli was the only notable absentee but he had been expected to report back to Italy for medical checks after being named in his country's provisional squad for Euro 2012.
Mancini and a number of players were invited to address the fans before being driven around town. Responding to big cheers, Mancini said: "I think we should be proud of these players because they did everything for you (the fans) - they wanted to win this championship for you."
City's title success will go down as one of the most dramatic in history, coming only on goal difference after Edin Dzeko and Sergio Aguero struck in injury time to see off battling QPR.
Mancini, wearing his trademark club scarf, said: "We had the best and worst five minutes in our lives.
"I think it was an incredible moment after we scored the third goal, but before it was very hard." games throughout the season.