Walter Mazzarri says Leicester’s win over Manchester City “won’t help” them, ahead of their clash with Pep Guardiola’s side on Wednesday.
The Hornets face the Citizens fresh from their thrilling 3-2 win over Everton and the Citizens' 4-2 loss to the Premier League champions.
Ahead of the tie at the Etihad Stadium, the former Inter boss says he expects to face a "very angry" City side.
He said: "I saw the game against Leicester. I was surprised, but in Italy, we have a saying: 'Each game has its own story'.
"This won't help us. We will find Manchester City very angry and focused, we won't have the luck that they will underestimate us."
He added, though, that Watford at their best can beat any team.
"I said this to my players. If we put ourselves in front of our opponents we can fight against any Premier League team.
"If we are 100 per cent ready, we can play against any team in the Premier League and battle for the three points.
"This is something that gives us a lot of positivity before the game."
And with Roberto Pereyra available again following his one-match suspension, Mazzarri has an extra attacking option, but revealed he is some way off announcing the team to face City.
"After such an intense game like the one against Everton, where we spent a lot of energy physically and mentally, it's still very early for me to decide on the team that will take part in the game against Manchester City," Mazzarri added.
"Some of the players trained individually, some trained with the whole team. In order to make a decision we will assess them tomorrow or the day after."