Napoli's hopes of pushing Juventus all the way in the title race diminished on Sunday and the boos rang out after it was held to a surprise 0-0 draw by bottom-of-the-table Chievo Verona.
Carlo Ancelotti's side is now already eight points behind Juventus, which beat Spal 2-0 on Saturday and looks to be on an unstoppable march to a record-extending eighth Serie A title.
Napoli is also just a point ahead of third-placed Inter Milan, which also won on Saturday. It would not have been the buildup it wanted ahead of Wednesday's Champions League match against Red Star Belgrade.
The result saw Chievo move onto one point. It has managed four draws all season but was deducted three points in September for false accounting.
It was Chievo's first match under its third coach of the season, Domenico Di Carlo. Lorenzo D'Anna was fired and Giampiero Ventura abruptly resigned just four games into his reign.
Napoli barely tested Chievo goalkeeper Stefano Sorrentino in the first half and it was Chievo that went closest through Joel Obi.
The hosts improved after the break but Lorenzo Insigne could only hold his head in his hands after firing wide from close range.
Inisgne went even closer with Napoli's best chance of the match but a trademark curling shot from the Italy international came off the far post.
Kalidou Koulibaly almost scored a spectacular late winner for Napoli but his overhead kick flashed narrowly wide.
CRAZY COMEBACK
Empoli scored in stoppage time to complete an astonishing comeback from two goals down despite Francesco Caputo missing a penalty.
Matias Silvestre headed in a corner in the 92nd minute to secure a 3-2 win over 10-man Atalanta.
Atalanta, which had won its previous five matches, went 2-0 up thanks to goals from Remo Freuler and Hans Hateboer.
Its second goal came seconds after Caputo had fired his spot kick off the crossbar following an Andrea Masiello handball.
Antonino La Gumina got Empoli back into the game shortly before halftime and also had a hand in the equalizer when Masiello deflected his effort into the back of the net.
Atalanta midfielder Josip Ilicic was sent off six minutes from time for dissent after he had a goal ruled out for offside.
Empoli moved a point clear of the relegation zone while Atalanta slipped to ninth.
OTHER MATCHES
Parma climbed up to sixth in Serie A after goals from Gervinho and Bruno Alves earned it a 2-1 win over Sassuolo.
It is its first season back in the top flight since going bankrupt in 2015.
Parma is two points behind fourth-placed Lazio, which hosts fifth-placed AC Milan later.
Elsewhere, Fiorentina was held to a 0-0 draw at relegation-threatened Bologna.
