The Partenopei coach has acknowledged that his side face a tough task in overhauling first-placed Juventus but says "anything can happen" in football
The Bianconeri currently occupy top spot in the league, boasting a nine-point cushion, but the 51-year-old is refusing to give up on the Scudetto.
"No, there is no regret for not being closer to Juventus in the table," he told reporters ahead of the match.
"There are still seven games to go. Of course it is very unlikely that we can finish on top, but in football everything can happen, so you never know.
"Once again I am pointing out that we have been enjoying a great season. Looking at our numbers, we have got 14 points more than last season."
Looking ahead to the San Siro clash, Mazzarri said he was expecting a great encounter and warned his players not to underestimate Giampaolo Pazzini, who is expected to deputise for the suspended Mario Balotelli.
"It is going to be a fascinating game," he continued. "Games like these do not need any further presentation. We will have to play at our best level.
"Milan have changed a lot this year, but despite integrating many new young players, the team has managed to remain at high levels.
"Being satisfied with a draw tomorrow is not our way of thinking. We are leading now, but never take anything for granted. Only at the end we will count our points.
"In my opinion Pazzini is a great player, and they also have so many champions. Besides, they were doing well even before Balotelli's arrival."