Los Che will host the Ligue 1 leaders at the Mestalla in the first leg on Tuesday.
"PSG play very well on the counter-attack with strong strikers and they are dangerous," he told reporters. "But we can be dangerous playing at home − we're strong at Mestalla.
"From the first minute we have to believe in our chances and our attitude towards the game will be very important tomorrow night.
"It's difficult to say when a team is going through their best moment, but we have improved since the draw was done in December. We have to be focused, trust our chances and work hard every day to carry on improving."
Valencia will head into Tuesday's clash on the back of a 1-0 away win against Celta Vigo in La Liga on Saturday.