The Giallorossi have won all three of their opening games and are level on nine points with Napoli at the top of the Serie A table.
It is an unusual start for Roma, who have not won their opening three games since the 2007-08 campaign.
"A long time had passed since we last had such a good start," Totti told the Roma Channel.
"I think that with respect to previous seasons, we have a more united group, capable of making a difference at any time.
"With the fighting spirit the team is showing in every game, I believe we can have a say but the season is long.
"The derby is a different game from any other but we know what to expect."
An inspired Napoli travel to San Siro to face AC Milan looking to end a successful week on a high note.
Lorenzo Insigne scored the decisive goal as Napoli tasted victory over Borussia Dortmund in their Champions League opener.
The result followed their 2-0 triumph over Atalanta and continued Rafa Benitez's winning start to life as Napoli coach. Benitez replaced Walter Mazzarri this summer.
Napoli were not the only Italian side to prevail this week in Europe's elite club competition as Sunday's rivals AC Milan claimed a 2-0 home triumph over Celtic on Wednesday.
The Rossoneri hope that result can spark their season into life as they have mustered just one league win so far.
Juventus were unable to make an Italian hat-trick in Europe's top competition. The Serie A champions were held to a 1-1 result by FC Copenhagen in Denmark.
That outcome followed their 1-1 draw at Inter Milan last Saturday. Antonio Conte's side host Hellas Verona next.
Inter Milan visit bottom-side Sassuolo confident of extending their three-match unbeaten run.
Promoted-side Sassuolo have the worst defence in the competition and have no points to their name.
Genoa expect to build on their stunning victory against city rivals Sampdoria when they host Livorno.
The Grifoni began the season with two defeats but an inspired performance saw them brush aside Samp 3-0 last Sunday.
Samp, meanwhile, take on Cagliari in Trieste looking to make amends after their dismal showing in the derby.
Catania will have to show a drastic improvement in attack if they are to take their first points of the campaign against Parma this weekend. The Sicilians have found the net just once.
Udinese travel to Verona to meet Chievo looking for their first win away win this term.
Fiorentina must overcome the absence of injured striker Mario Gomez when they take on Atalanta in Bergamo.
Gomez sustained a knee injury in last Sunday's 1-1 draw against Cagliari and will be sidelined for two months.
Bologna welcome Torino to the Renato Dall' Ara stadium determined to claim their first win of the campaign. The Rossoblu have mustered just two points from their opening three games.