The Spaniard was a doubt for the match after missing the defeat to Shakhtar Donetsk on Wednesday, with Guardiola confirming his playmaker was a concern ahead of the top-of-the-table clash.
And Guardiola confirmed that Silva declared himself fit for the derby after he and Kevin De Bruyne reported for training on Friday while the rest of the squad who travelled to Ukraine were given the day off.
“He's going to play,” Guardiola said. “After the game he had a bit of doubt that's why I said it, but today he arrived and said he's really good so he's going to play.”
However, City do have concerns over two of their defenders, with Guardiola admitting he is awaiting late fitness tests of captain Vincent Kompany and make-shift left-back Fabian Delph.
The duo, like Silva, missed the 2-1 Champions League defeat this week after Kompany experienced some discomfort while Delph was ill.
“Vincent, before the game against Shakhtar, felt something,” he added. “He was not comfortable and couldn't play.
Manchester United vs Manchester City derby classics
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“Delph was sick, vomit and fever the day before.
“The only guys who didn't play because they needed a rest were Kyle Walker and Nico Otamendi. Today they are off so I don't know - but tomorrow we will check how the conditions are.”
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