While they now cannot catch Juventus, who sealed another Serie A success on Sunday, the Partenopei remain well placed to play in Europe's elite competition next season as they are seven points clear of third-placed AC Milan with three games to go.
They can guarantee runners-up spot with victory at mid-table Bologna on Wednesday although Mazzarri is not taking anything for granted against a team he refers to as Napoli's "bete noire".
"Let's remain focused, we still need three points," said Mazzarri on the club's official website following their 3-1 win over Inter Milan.
"I am satisfied with this victory, but I was afraid that we would not close the game because although we had many efforts at goal they managed to draw. However, we were able to impose our supremacy and achieve a well-deserved victory."
"Now we must go on with this intensity. On Wednesday we are going to play against Bologna, our bete noir.
Milan will also hope to move one step closer to Champions League football when they play rock-bottom Pescara. The Rossoneri went four points clear of fourth-placed Fiorentina, who next travel to relegation-threatened Siena, by edging out Torino on Sunday and will be looking to carry that momentum into their clash at the Stadio Adriatico.
"The match against Pescara will be fundamental. Winning there and maintaining our lead on Roma and Fiorentina would be great," said vice-president Adriano Galliani.
Roma can go level on points with Fiorentina if they can follow up Saturday's win at La Viola with another three points against Chievo in Tuesday night's only fixture.
The Giallorossi can approach this match with confidence as they are unbeaten in their last six matches in all competitions and have claimed four wins in their last five.
Juventus will be aiming to celebrate claiming back-to-back Scudettos at Atalanta on Wednesday, but they must do so without Paul Pogba, whose season is over after being suspended for three matches for spitting at Palermo defender Salvatore Aronica yesterday.
At the other end of the table, Palermo host Europa League chasers Udinese hoping to close the three-point gap on fellow strugglers Genoa, who could move above Torino with victory over Giampiero Ventura's men.
Inter Milan have lost five of their last six matches in all competitions so will therefore be looking for a much-needed three points against Lazio, Sampdoria host Catania, while Parma travel to Cagliari.