Serie A leaders Napoli suffered only their second league defeat of the season as they lost at home to Lazio, who dropped to second in the table.
The only goal of the match was scored by Matias Vecino in the 67th minute with a superb strike from outside the penalty area.
Serie A’s top goalscorer Victor Osimhan, with 19 goals in the league, came closest to equalizing but saw his header bounce off the crossbar.
Lazio’s Serge Mlincic-Civic also hit the woodwork with a free-kick.
Vicino’s goal was the first goal Napoli had conceded in six games.
Napoli are aiming to become Italian champions for a third time, with their last success coming in 1990.
Despite the loss, they are still in a dominant position as they are 17 points ahead of Lazio, who have moved a point clear of Inter and AC Milan and both Milan clubs have a game in hand.
AC Milan play at Fiorentina on Saturday before Inter host Lecce on Sunday.
