The Uruguay forward is missing from the squad following the injury he sustained in Europe, but the coach feels they can cope in his absence
The Italians travel to Milan without the services of star striker Edinson Cavani who has been ruled out of action after picking up a knock in the 2-0 win over Villarreal in the Champions League.
However, Mazzarri believes they can do well without him as he looked forward to the game.
"I am convinced we will do well in Milan, but we must not forget we are playing an excellent team," Mazzarri explained to the gathered press.
"They have been revamped under Claudio Ranieri and they are rediscovering themselves after winning two games on the bounce.
"Cavani? I still have faith as the player who replaces him will be good enough to cope. We will see."
Napoli are currently sixth in Serie A with seven points from four matches. Meanwhile, Inter have gathered only four points during that stretch.