Lazio have inflicted a first home league defeat of the season on Napoli to move into second in the Serie A table.
Matias Vecino scored the only goal of the game at the Diego Armando Maradona Stadium as Maurizio Sarri's side slowed Napoli's charge towards a first title in 33 years.
The defeat was Napoli's first in front of their own fans in the league since April 2022, and the first time they had even dropped points in Serie A on home turf since August.
However, Luciano Spalletti's side remain a commanding 17 points clear at the top of the table, with Lazio leapfrogging Inter Milan and AC Milan into second place.
The Milan clubs will have the chance to move back above I Biancocelesti when they feature over the weekend, but tonight's victory is a statement of intent from a side that are now unbeaten in their last five games, keeping clean sheets in all of those.
Napoli were on a run of five clean sheets of their own heading into this match, while the runaway Serie A leaders and top scorers had also only failed to find the back of the net twice in the league all season.
However, they were barely given a glimpse of Lazio's goal as the visitors put in a disciplined performance to pick up a famous win.
Victor Osimhen predictably came closest for the hosts, hitting the crossbar with a header before Giovanni Di Lorenzo saw his rebound saved.
That came just 10 minutes after Lazio had broken the deadlock through Vecino, whose crisply-struck first-time thunderbolt from 25 yards flew past Alex Meret in the Napoli goal.
The visitors almost doubled their advantage in the dying stages too, with Sergej Milinkovic-Savic hitting the post with a free kick in the final minute of normal time.
One goal proved to be enough, though, ending Napoli's eight-match winning streak in Serie A and inflicting just a second league defeat of the season on the champions-elect.
Lazio, meanwhile, have now kept eight away clean sheets this season, equalling their best-ever tally for a single Serie A campaign.
Barney Corkhill
