Stevan Jovetic scored twice to fire Fiorentina to a 3-0 win over Parma on Wednesday, and Mihajlovic wants that result to be a platform for La Viola.
"It was an important victory for us against a difficult rival," he said.
"I am very pleased not only with the result but with the fact that we were able to keep a clean sheet for the second time this season.
"We must show the same determination that we displayed against Parma when we take on Napoli.
"It will be a difficult game but we are ready."
With Fiorentina still without injured striker Alberto Gilardino, Mihajlovic will be hoping Jovetic can again deliver in front of goal.
The Montenegro forward opened his goal tally in midweek and will play alongside Juan Vargas and Alessio Cerci in attack.
"Jovetic is crucial for us," Mihajlovic said. "He has finally scored and I'm very happy for him.
"Now he will have more confidence."
Napoli, meanwhile, will be looking to bounce back from Wednesday's 1-0 defeat at Chievo - their first loss of the campaign.
The hosts will fancy their chances as they have not lost at the San Paolo since April 17.
Moreover, Gokhan Inler, Marek Hamsik, Ezequiel Lavezzi and Edinson Cavani are expected to start against Fiorentina.
Hamsik, Inler and Cavani came off the bench against Chievo while Lavezzi rested in midweek.
"We don't have time to dwell on this defeat," coach Walter Mazzarri said.
"We must put it behind us and focus on our next game against Fiorentina."