Unbeaten Udinese have a one-point lead over Lazio at the scudetto summit, with Napoli a further three points behind that in fifth.
And while no-one else seems to expect Udinese to hold on to their lofty perch, Mazzarri believes they are there on merit.
"For me I think they can win the title, that's what the pitch says," Mazzarri proclaimed.
"The numbers say that on Wednesday they are the favourites, even though we can match them.
"Our fans have to understand we're playing the best team in the league, we need them to get behind us.
"Everyone, also those in the stands, needs to think that we're playing a team as good as AC Milan, Inter Milan and Juventus.
"I hope we will play as well as we did against Manchester City and Bayern Munich. In fact, we'll have to play even better because tactically tomorrow will be even more difficult. We need the atmosphere to lift us."
Napoli finished third last season and qualified for the Champions League for the first time in 21 years.
But Mazzarri believes their involvement in that competition is behind their inconsistent form.
Although they have beaten the likes of Inter and Milan and drawn with City and Bayern, they have lost to Chievo and Parma.
"We're paying more than the others for our involvement in the Champions League because we're not used to it and we're not managing to repeat our performances in the league because there's not much recovery time," he said.
"Maybe it was a mistake to beat Milan and Inter because if we hadn't, it would have created less expectation.
"We're doing something exceptional. We've earned eight results (wins or draws) in 10 matches in just a few days and yet this is far too quickly forgotten. We need balance here, rather than scepticism."