The 51-year-old is fearful of a potential banana skin against Cittadella, especially given the international commitments of a number of players this week
The San Siro giants have been forced to contend in the third qualifying round of the tournament after stumbling to a ninth-place finish in Serie A last season, and although the Nerazzurri remain firm favourites for the encounter, Mazzarri is determined not to underestimate their opponents.
"Yes, that's absolutely true [the match is tricky] because it comes before the league has even kicked off and we haven't played a single meaningful match yet," warned the Italian to Inter Channel.
"Regardless of who you're up against, you always risk subconsciously underestimating your opponents. There are plenty of pitfalls in August fixtures.
"We must be aware of that when we go out there and take control of the game, showing that we're focused and paying attention to every little detail needed to win it."
Inter are further hampered by the fitness of players who were involved with their national sides during the past week, but Mazzarri insists tiredness will not be an excuse heading into the clash.
"Some of the lads are a bit more tired than others, those who played a lot with their national teams," added the 51-year-old.
"[Rodrigo] Palacio, for example, was tired and he didn't even take part in the training match today. We can't use that as an excuse though.
"The lads need to recover and get some rest overnight to put in a good performance tomorrow so that we have a chance of going through."