Napoli's nightmare season continued on Sunday after crashing to a 3-0 defeat at Torino, while AC Milan consolidated their place in Serie A's Champions League positions with a 3-0 win at Empoli.
Livid Napoli fans launched flares onto the pitch at the Stadio Olimpico Grande Torino during a humiliating loss for the troubled champions, who have sunk down to ninth place.
Last season's historic Scudetto has now been forgotten as Napoli plunge deeper into crisis with each passing week, their third defeat in four matches in all competitions fully deserved after a shambolic display in Turin.
Without Nigeria striker Victor Osimhen, Walter Mazzerri's side failed to score for the fourth straight match and are completely unrecognisable from the team which cruised to title glory last term.
Napoli are a full 20 points behind league leaders Inter Milan and are closer to the relegation zone than the top of the table.
Antonio Sanabria got the ball rolling two minutes before the break when he rolled home from close range, and things went from bad to worse in the 50th minute when debutant Pasquale Mazzocchi was sent off for a wild challenge on Valentino Lazaro.
Mazzocchi, who signed from Salernitana on Friday, had only been on the field since the start of the second half and two minutes later Nikola Vlasic doubled Torino's lead with a brilliant low strike from outside the area.
Napoli were all over the place and they should have been three down just after the hour mark when Sanabria hit the post and Duvan Zapata somehow didn't finish on the rebound.
However Alessandro Buongiorno made sure of an emphatic victory in the 66th minute when he thumped a bullet header past Pierluigi Gollini.
Milan cruise
A sumptuous early strike from Ruben Loftus-Cheek and Olivier Giroud's 31st minute penalty set third-placed Milan on the way to a win which was sealed by Chaka Traore with two minutes remaining.
Missing a host of players to injury and the Africa Cup of Nations, Milan took advantage of their closest rivals for the top four dropping points.
Stefano Pioli's team are six points ahead of fourth-placed Fiorentina who lost 1-0 at Sassuolo on Saturday, and a further point in front of Bologna in fifth following their draw at Genoa.
Milan have had a bumpy campaign riddled with injuries and questions over Pioli's future but Sunday's win was their fifth in six matches in all competitions.
"We went through a bit of a difficult period... We never listened to what other people were saying, we got down to hard work and that's why we won today," said Theo Hernandez, who was again deputising at centre-back.
France international Hernandez is a buccaneering left-back by trade but has been forced to move to the centre of defence by an injury crisis which has left Pioli without Fikayo Tomori, Malick Thiaw and Pierre Kalulu.
Empoli stay second-from-bottom after failing to win for the seventh straight match, Aurelio Andreazzoli's side missing seven first-team starters and no match for the rampant away side.
"It's in the difficult moments that you learn if people have given up on you, and that wasn't the case here," said Pioli.
"When things don't go well we stay together and we give each other a hand."
Milan trail city rivals Inter by nine points and are four behind second-placed Juventus, who play Salernitana later on Sunday.
Lazio warmed up for their midweek derby with Roma in the Italian Cup quarter-finals by winning 2-1 at Udinese and moving up to sixth.
