Tassotti spoke to Milan Channel about Tuesday's difficult trip to Eindhoven.
"All of our pre-season preparation has been aimed at this crucial game for the Champions League play-off," said Tassotti.
"We played the friendly games that we considered suitable, though of course this is not the same as playing a friendly or in Serie A.
"PSV are a team who keep the ball very well and know how to attack, so we will need to be very aggressive.
"Their stadium isn't very big, but it is a passionate atmosphere and the enthusiasm will make it difficult for us. We haven't had much time to study PSV, as we only began tactical discussions on Friday.
"The only doubts we have are wrapped up in the stamina and intensity, as obviously this is our first 'real' match of the season and it was tough to play at a high tempo in America with that heat.
"Now Tuesday's game is the only thing in our minds. We hope to get a good result, as getting through is fundamental for many reasons."
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