Napoli sit comfortably in second place.
"Tomorrow, whatever happens, I don't think we will be mathematically certain of Champions League qualification," said Mazzarri in his Press conference.
"The goal difference gives us an advantage, but if Milan were to catch us on points then the situation could change. We mustn't think about this now, nor look at what the other teams are doing.
"The lads have grown over the course of the campaign, as everyone feels important and I doubt the squad is thinking back to our defeat at San Siro in December.
"If you look back at our wins over Atalanta and Cagliari, you'll see we struggled to get all three points. Inter have more important players compared to these teams and face this type of game with their blood boiling. We need, as always, the perfect performance."