The reigning Premier League champions are already five points behind league leaders Chelsea in the table after four games.
"It is a very important game," FourFourTwo quotes Silva as saying. "They are first in the league and have more points than us. We can't lose on Sunday and let that gap get any bigger. So it is a very important game.
"It is early in this stage, it's still a long way to go in the Premier League and anything can happen, [but] yes, we need to win on Sunday because otherwise the gap will start to get too big."
Jose Mourinho's Chelsea side did the double over City in the league last season.