The Hornets host the Blues at Vicarage Road on Wednesday night and after their strong performance in the 2-2 draw at Stamford Bridge on Boxing Day, Flores is expecting a positive result against Guus Hiddink's men.
"I always think Chelsea are an amazing team. They have very good players, an amazing squad and a lot of possibilities to change players if they think something isn't good during the match, they can change for different variations," Flores said.
"It's very difficult to play against Chelsea; they have amazing power in terms of physicality, but we played against this team a month-and-a-half ago and we had the opportunity to win before finally we drew.
"Our expectation is very high; to be competitive and to play well, to make a balance with Chelsea.
"Of course, we are really positive we can do something good."
The Spaniard added: "We know they have the possibility to improve a lot because they've got Willian, (Diego) Costa, (Eden) Hazard, Oscar, (Nemanja) Matic, (John Obi) Mikel and (Cesc) Fabregas.
"They have amazing players, and with their reaction, of course they have the possibility to achieve amazing targets.
"But our work at the moment is to be confident, try to make life very difficult for Chelsea on the pitch, this is our work."