Napoli saw their push for a place in the Champions League next season suffer a setback as they were beaten 2-0 at Hellas Verona on Sunday.
Luca Toni netted both goals for Andrea Mandorlini's men, who took a big step away from the bottom three with victory at the Stadio Marc'Antonio Bentegodi, although they ended with 10 men after Jacopo Sala saw red.
Napoli, who beat Dinamo Moscow 3-1 in the Europa League on Thursday, could be forced to focus on making progress in that competition for their best chance of making Europe's elite club competition next season with Lazio able to move three points clear in third by beating Torino on Monday.
Juan Gomez wasted a one-on-one with Mariano Andujar with the ball going behind for a corner as Verona went straight for the jugular.
Soon after, the hosts took the lead with Toni making the most of a mix-up between Andujar and Giandomenico Mesto to score.
Verona kept their finger on the pulse, creating chance after chance to increase their lead against a Napoli side who did not seem to know what was hitting them.
Bosko Jankovic was next to threaten Andujar's goal, only just missing the target before Napoli started to respond.
Dries Mertens and Duvan Zapata both had chances to level before the interval, but it was again the home side who started strong after the break.
Toni went close five minutes in, but he did not waste his next opportunity as he beat Andujar with his left-foot effort to double Verona's advantage.
It knocked the stuffing out of Napoli, who were looking tired after their exertions on Thursday.
They tried to make things interesting with Gokhan Inler's effort saved by Francesco Benussi before Manolo Gabbiadini was sent on by Rafael Benitez.
He rattled the left-hand post before clattering Sala with a foul which earned him a yellow card.
Sala's angry reaction secured a second yellow for him, reducing Verona to 10 men for stoppage time, but the hosts had no trouble holding on to victory.