The Eastlands outfit will host Birmingham on Saturday and Mancini is set to rotate his squad, as he does when his side are in midweek action in the Europa League, with the game coming so soon after playing United.
"We are going to change some players," he said. "If we play a Europa League game it is usual for us to change six or seven because it is impossible to be a fantastic team when you are playing every three days."
City chief executive Garry Cook has travelled to Abu Dhabi, homeland of owner Sheikh Mansour, and speculation suggested he had gone with a list of transfer targets, although Mancini played down such talk.
"I think he has gone to watch the grand prix," he joked, with the final race of the Formula 1 season taking place in the Emirate state this weekend.
"It is a normal board meeting in Abu Dhabi.
"Anything can happen in January. If some players want to leave because they want to play somewhere else then it is different. But at the moment there are no problems."
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