Mazzarri's Napoli have been one of the big stories to come out of the UEFA Champions League this season.
The Naples-based outfit with their own brand of attacking football qualified to the knockout stages via the 'Group of Death' along with Bayern Munich but ahead of Manchester City and Villarreal. They also look odds on to reach the quarter-finals after defeating Chelsea 3-1 in the home first leg of their last-16 tie with the former Barclays Premier League champions.
However, Mazzarri, like so many experts and fans across the world, was taken aback by the way European champions Barcelona crushed Bayer Leverkusen 7-1 (10-2 on aggregate) on Wednesday that he believes no team can stop the Catalan machine from defending their trophy - even if former Germany international Rudi Voller thinks Napoli can stand up to Barca.
"I thank him [for the compliment] but that the Spaniards at this moment remain elusive," Mazzarri told reporters at a press conference on Thursday.
"They are on another level."
It's true it would be hard for any team to think about stopping Lionel Messi and Company, especially given the type of form the Argentinean has shown in Europe. He easily leads the goal scoring charts following his record five-goal haul against Leverkusen.
All Mazzarri wants to do is take things one step at a time which for Napoli means finishing the job at Stamford Bridge in next week's second leg with Chelsea.
"It will be tough, as we saw from how AC Milan suffered against Arsenal," he said, referring to the Rossoneri's 3-0 defeat in north London which almost saw them get knocked out of the competition.
"And our opponents, I think, are even stronger than [Arsene] Wenger's team."
In preparation for the Chelsea clash, Napoli are set to rest star striker Edinson Cavani for Friday's game against Cagliari in view of next week's showdown at the Bridge.