Roma top the table with a maximum 18 points from six games while the Nerazzurri sit fourth, just four points behind Rudi Garcia's men.
Mazzarri believes their early-season clashes with three top-five teams Juventus, Fiorentina and now Roma will give them a good indicator of how their season will pan out.
"Saturday's match represents another important test for us," the former Napoli boss said on Friday.
"It's another test that we should pass at best in order to improve and become even more competitive compared to the first six matches.
"If you take a look at the calendar, after tomorrow's match, we'll have played against the three top teams, whereas other teams haven't done that so far so it puts us in a good place.
"These matches are important to test our condition and our chances in Serie A."
Mazzarri also hailed the impact of Garcia on Roma's fortunes, after the former Lille man was brought to the Italian capital in the off-season following caretakover boss Aurelio Andreazzoli's spell in charge.
"My impressions about Garcia are very positive. He seems to be very practical," Mazzarri said.
"I've heard that the players like him and believe in him, therefore this means he is doing a great job.
"I believe this is exactly what a coach has to do if he wants to succeed.
"I have a positive impression about him and his work with the team but I can't say much more than this, because I don't know him very well, I haven't had the chance to talk to him.
"This is just the feeling you have when you see a professional manager, and see how he behaves with the team and how the players talk about him."
With neither side yet to taste defeat in Serie A so far this season, Mazzarri is confident Saturday's clash will be "captivating" to watch.
"If we analyse what the two teams have proved up to now, I believe that tomorrow's match is going to be an important and also beautiful match because both teams have created many chances, scored many goals and conceded very few goals to their opposition," Mazzarri added.
"To tell you the truth, if we consider the figures, they have made a better performance compared to us because they scored more goals.
"I believe they have scored just one more goal but also conceded two goals less than us, therefore they're the leader of the table.
"In any case, we're ranking right behind them so it should be a beautiful and captivating match to watch."