AC Milan edged ahead in the Serie A title race as Olivier Giroud gave them what could prove a crucial victory over fellow challengers Napoli.
The French striker stuck out a boot to steer in Davide Calabria’s low, driven cross early in the second half.
Napoli pushed hard in search of a route back into the game but could not find a way past a stubborn visitors defence.
The win takes Milan top on 60 points, two points better than fierce rivals Inter Milan and three ahead of Napoli.
It was a high-quality game between two sides, but one low on clear goal-scoring chances.
Victor Osimhen saw a couple of shots saved by Mike Maignan and substitute Adam Ounas flashed an effort wide as the home side desperately sought parity.
Milan felt they should have had a penalty for a foul by Kalidou Koulibaly on Ismael Bennacer but the referee waved away the shouts, as he did at the other end for Fikayo Tomori’s challenge on Osimhen.
It was an eventful game for Giroud.
The ex-Arsenal and Chelsea player suffered a cut in the first half that appeared as though it might end his game, but he stayed on and struck the decisive blow before limping off after falling awkwardly.
In more positive injury news for Milan boss Stefano Pioli, Zlatan Ibrahimovic made his return as a late substitute to help see out the win.
It means a two-point lead at the top, although remaining champions Inter – who were 5-0 over Salernitana on Friday – have a game in hand.
Juventus remain an outside bet for the title after extending their unbeaten league run to 14 games with a 1-0 win over Spezia.
Alvaro Morata scored the only goal for Massimiliano Allegri’s side, who were not at their best but dug deep for a vital win.
Juve move on to 53 points in the fourth and final Champions League spot, where they sit six points above fifth-placed Atalanta, who have a game in hand.