The Hornets have not beaten reigning Premier League champions City since 1989 and have lost every meeting between the sides since 2007, but Ranieri remained upbeat.
“I know I go against a big fantastic team. We know, but we have to play and we try to do our best,” the Watford manager said.
“Of course I want a clean sheet, not only one, but I believe we can achieve a clean sheet if we continue to play in this way.”
Going into November, the Hornets faced a daunting run of fixtures including Leicester, Everton Manchester United and Chelsea but managed to win 5-2 at Everton and beat United 4-1 at home in what proved to be Ole Gunnar Solskjaer’s final match in charge.
Watford also pushed the current league leaders Chelsea in midweek, with even Thomas Tuchel admitting that his side did not deserve all three points from the encounter.
“I am very confident with my players but of course you know I am a pragmatic manager and I’d like to take some points,” Raniaeri said.
“Because if you play well once, twice, three times without taking a point, after it’s not good.
“Now is the right moment to take points, we need points, we are in the battle for relegation and then we have to react, every match we have to react, every moment we have to react, every time.”
Manchester City have lost just two league matches this season, winning 10 out of their first 14, while Watford currently sit in 17th place, just three points ahead of the relegation zone.