Benitez wary of Bologna under new coach
The Napoli coach has witnessed his side go eight games unbeaten in all competitions, including a 3-0 victory at Verona in their last Serie A outing last weekend.
Next up for Napoli is a visit to strugglers Bologna, who have just one win in their last nine league matches.
That poor form saw the dismissal of Stefano Pioli, with Ballardini taking over on a short-term deal that began with a solid 0-0 draw at home to Lazio last Saturday.
And Spaniard Benitez believes his players face a difficult challenge in Sunday's showdown.
"We were determined in Verona and won that game," he said. "Now we must continue taking that approach in Bologna.
"When a tactician is replaced, it's never good news, but now Bologna will be more dangerous because they are eager to prove themselves under Davide Ballardini. Every player gives 100 per cent against Napoli anyway."
Juventus are in prime position to claim a third straight title in Italy, with Napoli third, 10 points adrift of Antonio Conte's side,
But Benitez remains optimistic of his side's chances.
He added: "Our objective is to improve.
"The first half of the season has been very positive and you can see the team growing. If we look at last season's squad, it is inferior to the current crop and that pleases me.
"We are working one day at a time, one game at a time, so it is too early to make predictions. The important thing is for the squad to believe in itself. If we keep playing this way, then we'll go far."