A late strike from Ruben Vezo secured all the points for the home team, who have now gone six matches unbeaten in La Liga.
"We had to be patient and insist on doing the things we needed to score the goal," Pizzi told reporters at a press conference.
"When you're playing a team with a lot of people in defence, it's hard to get through. Their goal brought impatience and nerves and forced us to put in even more effort."
Valencia currently sit eighth in La Liga.