The Argentine striker was handed the poster by a member of the the crowd during the celebrations and was pictured holding it above his head on Sky Sports News.
The sign could be a reference to Manchester United manager Sir Alex Ferguson’s claim that his side would never be underdogs to City. “Not in my lifetime,” said the Scot.
A City spokesperson said: “The creation of the tasteless material is in itself reprehensible. 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 for any offence or distress caused.”
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