Silva has made a remarkable recovery from the hamstring injury that kept him out of the midweek UEFA Champions League defeat to Borussia Dortmund and could come into contention at the Etihad Stadium.
"We will try with David," said Mancini, who will also monitor the progress made by fellow injury victims Gael Clichy and James Milner.
"It is a big risk because afterwards we have a lot of games between now and the end of December and we need all the players to recover."
Manchester United are currently three points clear of their neighbours and Mancini insisted: "They can lose because they have three points more. We have three points less and we can't lose.
"They are better than us at this moment.
"We have only been here for two years. They are used to playing these games in the title race for 20 years. They have won everything for 15 years.
"You can't change this in two or three years. You need more time.
"For this reason they have a small advantage."
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