Despite the Partenopei's flyaway start to the domestic season, Mazzarri has come under fire for his apparent reluctance to treat the Europa League equally seriously, with a second-string outfit suffering a disappointing 3-1 loss to Dnipro on Thursday.
To add insult to injury, Juventus were finally able to pull clear at the top of the table courtesy of victory in Turin last weekend, but Mazzarri is ready to restore his preferred XI in a bid to stay in touch with the reigning champions.
"I'm happy with how much the players had improved since the PSV game," he told the Gazzetta dello Sport after Thursday's game.
"The second goal probably could have been avoided and then things might have gone differently.
"The fans can say what they like and their opinion is respected. All I can say is that every single player is committed.
"The squad I saw tonight [Thursday] was definitely one that can compete.
"We have only played eight league games and we have three more left to play in Europe.
"I'm already thinking about what we need to do against Chievo, who will be fired up at the San Paolo."
Slovakian playmaker Marek Hamsik, who did not feature in the Ukraine, is still seething after Saturday's crucial defeat to Juve.
"The loss has put us all in a dark mood," he said. "It has infuriated us to the point where we have more desire than ever before to bounce straight back with a win against Chievo.
"We're playing well but we must be aware of the hidden pitfalls in the forthcoming matches."
Chievo are floundering at the wrong end of the table but new boss Eugenio Corini has collected four points from the last two games.
Flying Donkeys midfielder Adrian Stoian is optimistic ahead of the trip to Campania, saying: "We were the underdogs against Fiorentina but we got an impressive draw.
"We'll go to the San Paolo with the desire to continue where we left off against Sampdoria. I believe we can do it."