Patrick Cutrone's winner at Napoli shot promoted Empoli seventh in Serie A
Empoli dealt a blow to Napoli's hopes of a first Serie A crown since the days of Diego Maradona after a stunning 1-0 win which gives Inter Milan a chance to take firm control of the title race.
Patrick Cutrone's bizarre winner with 20 minutes remaining in Naples fired promoted Empoli seventh in Italy's top flight and leaves Napoli fourth, three points behind leaders AC Milan who drew at Udinese on Saturday.
Luciano Spalletti's side could be four points off the lead by the end of the day if Inter win Sunday's late match against struggling Cagliari, with the reigning champions ensured of top spot with a victory at the San Siro.
Napoli held top spot before last weekend's matches but have now also been overtaken by Atalanta, who moved into third following their 2-1 win at Verona earlier in the day.
"We weren't very good in expressing quality when it was time to strike in the match," said Spalletti to DAZN.
"In those moments when we had them backed into their own area we weren't clear-headed enough to make the right choices."
It was another impressive away victory for Aurelio Andreazzoli's side after their shock win at Juventus back in August, and it came thanks to an odd goal.
Cutrone rose highest for a corner and his flick flew at Andre-Frank Zambo Anguissa, who minutes after his return from injury headed his clearance into the back of Cutrone's head and then watched the ball fly back into his own goal.
"The goal was a set-piece play that we've been working on for a long times," joked Andreazzoli to DAZN.
It was an unfortunate way to lose for Napoli who had 30 shots, struck the bar through Eljif Elmas in the first half and had a Juan Jesus goal ruled out for offside nine minutes before Cutrone's winner.
They now travel to Milan next weekend hoping to not fall further behind the pacesetters with key players either out or only just returning from injury.
After the match Napoli said that tests on Piotr Zielinski, who left the field in the 22nd minute with respiratory problems, had found nothing while Elmas had picked up a calf injury.
Empoli meanwhile were celebrating moving above Roma and Lazio -- 2-1 losers at Sassuolo -- and just two points behind Juve who drew at Venezia on Saturday.
"The boys believe, they've seen that they can do what we said they could," added Andreazzoli.
"And it's the truth, I've not told them stories and the result is that they play like they have done in recent weeks."
Atalanta are two points behind Milan after coming back from Giovanni Simeone's 12th goal of the season thanks to strikes in either half from Aleksei Miranchuk and Teun Koopmeiners at Verona.
A sixth straight league win on the road also has Gian Piero Gasperini's side seven points above fifth-placed Fiorentina in the race for the Champions League.
"Turning the result around was a show of force, we deserved to win even though it was an even match," said Gasperini, who seemed quietly confident his team could have a say in the title tussle.
"Today we took a step forward, regarding mentality and determination, otherwise you don't win these kinds of matches."
Defeat for Verona meanwhile was their first at home since Igor Tudor took charge in mid-September and leaves them 11th on 23 points, one ahead of Torino who beat Bologna 2-1 in Sunday's early match.
The hard-fought win will be a boost for Atalanta after they missed out on the last 16 of the Champions League following Thursday's home defeat at the hands of Villarreal.
They will be in Monday's draw for the Europa League play-off round after finishing third in Group F behind La Liga outfit Villarreal and Manchester United.