By ESPNSTAR.com staff
The Stadio San Paolo has been an intimidating fortress that few European sides care to visit.
Last season, Chelsea suffered a rude shock when they were defeated 3-1 by the Neapolitan side in the Champions League round of 16 stage.
But the Serie A side have finally been defeated at home after PSV came away with a win with a similar scoreline.
With Napoli having already qualified for the round of 32, an understrength squad was sent out in a bid to preserve fitness levels for the upcoming league games. Despite this, however, Mazzarri felt that his team were unlucky as they did enough to at least come away with a draw.
Goalkeeper Antonio Rosati, in particular, committed several mistakes and the strikers were repeatedly profligate.
"Rosati was unlucky, just as our forwards were," the Italian commented.
"We created many scoring opportunities, but only managed one actual goal. Just as a player can miss a clear chance, a goalkeeper can make mistakes too.
"Aside from that, I saw some young lads improving like Omar El Kaddouri. The result does not reflect the real game.
"We are angry anyway, as we never like losing, let alone in Europe at the San Paolo. Unfortunately, they scored three goals with two and a half chances."
He did have some reason for cheer with the return from injury of Goran Pandev as well as a promising debut by Roberto Insigne, who is also the the younger brother of 21-year-old prodigy Lorenzo.
"Pandev looked good and he doesn't have 90 minutes in his legs yet, but I know I can count on him for at least part of this weekend's game against Inter.
"[Roberto] Insigne is a great talent and needs to bulk up a bit, but he stepped on to the field with incredible character.
"The brothers have different characteristics, but are both very talented. Now we have to see whether he'll step up the various categories with us or somewhere else."
Napoli have a crucial game against fellow Serie A title hopefuls Inter Milan at the San Siro on Sunday night.