Samp will defend a 1-0 lead in Genoa and Mazzarri warned: "I tell my players that you only get a win by working hard to improve yourself. We must always try to build on what came before to do better in the future.
"In football the unexpected is always around the corner, but it is also true that often results depend entirely on your performance."
Samp can be excused for feeling over-confident after four wins in their last four official games.
"I want my players to focus only on the field and how to best work as a unit during the active and passive spells of the match. I don't care if we are in Europe, home or away, the approach remains the same," he told the official club website.
"The opponent needs to be dealt with, but it is more important that we have our own identity and the conviction we can win everywhere. Never feel sated, never!"