Three years of simmering resentment at the way Hargreaves' long-term knee injuries were initially handled by the Red Devils medical staff spilled over this week.
In the aftermath of his goalscoring debut in City's Carling Cup win over Birmingham, Hargreaves claimed he felt "like a guinea pig", such were the treatments he was forced to undergo.
To Hargreaves, the whole problem had been exacerbated by injections he was advised to have by United as part of his attempts to combat a tendinitis problem that first came to light in 2007, when he was still at Bayern Munich.
Evidently, Ferguson, and United, are unhappy with the 30-year-old's observations, their staunch rebuttal merely fuelling what was always likely to be a high-octane duel on October 23, which Hargreaves could be at the centre of in more ways than one.
"We have to be calm and think about his body," said Mancini. "If everything is okay in the next two or three weeks, maybe he can play against Manchester United."