Gazzetta dello Sport described it as "extraordinary normality". A team such as Napoli – one with a wage bill a fraction the size of Europe's elite and who were playing their football in Italy's third tier as recently as 2006 – should not be able to defeat Chelsea as easily as they did on Tuesday night. And yet it did not come as a total surprise when they did.

"If you had said six months ago that Napoli would beat Chelsea 3-1, it would have been time to dial [Italy's medical emergency number] 118," writes Marco Ansaldo in La Stampa, but the world has moved on in the intervening period. Chelsea are in the midst of perhaps their worst season since Roman Abramovich bought the club in 2003; while Napoli's own domestic form has been indifferent, they have already defeated Manchester City and drawn at home to Bayern Munich in the group stage of this year's competition. Already Italy is growing accustomed to seeing them raise their game on this stage.

"Warmer and warmer, brighter and brighter, Italian football's spring brings another glorious night in the bubble of enthusiasm that is the San Paolo," writes Paolo Condò in Gazzetta's front-page editorial. "Six days after Milan's portentous evening, now Napoli too clambers aboard the Champions League train thanks to the usual – and this might seem like a contradiction, but it isn't – game of their lives."

This was not only a victory for Naples, but in the eyes of many Italian journalists also a victory for financial prudence. "From the team owned by Abu Dhabi's Sheikh Mansour to that owned by the Russian oligarch Abramovich, the result doesn't change. Indeed, it grows in favour of Napoli," says Marcello Di Dio in Il Giornale. "Before financial fair play has even had the chance to balance things out on the field (Napoli have had five years of profit, Chelsea have are €75m in the red), the Blues fell at San Paolo just like Manchester City."

La Repubblica's Fabrizio Bocca picked up a similar thread on his blog, noting: "Chelsea might have bigger names, more money, a group of players who are on the whole more famous, but they don't have the inspiration and the class of people like [Ezequiel] Lavezzi, [Edinson] Cavani and also [Marek] Hamsik." In Corriere della Sera Luca Valdisseri credited "a heart as big as the city".

There was recognition, too, however, that this was a victory born in part of Chelsea's deficiencies as well as Napoli's merits. "Coming up against Chelsea today is like kicking a hole in a wall and finding €1,000," writes Ansaldo in La Stampa. "The defence is a masterpiece of disorderliness and not just because of [John]Terry's absence. We have never seen the Londoners in such a state, not even during the crisis that led to the sacking of [José] Mourinho. Poor [Petr] Cech now plays with a helmet not to protect his head from blows but to keep himself from tearing his hair out in desperation."

Gazzetta dello Sport's player ratings singled out Terry's replacement, Gary Cahill, for particular criticism. "Seeing him in action, we can completely understand why Villas-Boas did everything, right up to the last moment, to get Terry back," says Nicola Cecere of a player whose performance was rated as a 4.5 out of 10.

The only regret is over Napoli's failure to put the tie beyond doubt. "They could have sealed their qualification for the quarter-finals already in the second-half at San Paolo, as Milan did against Arsenal," writes Ansaldo. "A question of experience. It would be terrible if in three weeks time they are left to regret the goal Lavezzi missed at 2-1 and the incredible clearance off the line on Maggio's shot that would have made it four."

But Gazzetta's Luigi Garlando speaks for the majority in noting that the team had still put themselves in a strong position. "If Napoli had not messed up two ready-made goals, the trip to London would have been a student's holiday, but as it is this will more than do," he writes. "Arriving among the top eight in Europe seems more of a reality than a dream."