AC Milan have lost more ground on league leaders Inter Milan and also lost another important player ahead of the derby as it drew 0-0 against Juventus at San Siro
Key forward Zlatan Ibrahimovic limped off in the 28th minute with an apparent achilles issue.
The 40-year-old Swede will likely join several other Milan regulars on the injury list.
Milan slipped to third in Serie A, below Napoli on goal difference -- although head-to-head record is the first tiebreaker at the end of the season.
Inter, who have played a game less than their nearest rivals, are four points clear at the top going into the international break.
When action returns in the domestic league, Inter will host Milan in the latest instalment of the Derby della Madonnina.
Juventus moved to within one point of the top four and the Champions League spots.
The Rossoneri had the best chances and more of the play, but both teams struggled to carve out clear scoring opportunities.
Juve and Milan drew 1-1 in Turin in September with Sunday's result ensuring this season was the first time in 30 years that both league matches between the two were drawn.
Meanwhile, Lorenzo Insigne sent a clear message to Napoli fans after scoring in a 4-1 win over bottom club Salernitana.
The Napoli captain celebrated by pointing to the badge on his jersey and clearly saying to the camera, in Italian, "I love you, I will always love you" -- after slotting home a second-half penalty.
It was the 30-year-old Insigne's first goal since signing a pre-contract agreement to join MLS side Toronto FC at the end of the season.
Juan Jesus gave the hosts a 17th-minue lead before Federico Bonazzoli netted a surprise equaliser for Salernitana.
However, Napoli restored their advantage on the stroke of halftime when Dries Mertens converted a penalty after Elif Elmas had been brought down.
Amir Rrahmani extended Napoli's margin before Insigne netted from the spot -- marking his 115th goal for the club to go level with Diego Maradona.
Salernitana remained stuck at the bottom of the table, eight points from safety.
New signing Sergio Oliveira scored his second goal in as many league games for Roma in their 4-2 win at Empoli.
Tammy Abraham scored twice and Nicolo Zaniolo also netted for Roma, who struck three goals in the space of four first-half minutes to move above Lazio and Fiorentina into sixth.
Former Cagliari forward Riccardo Sottil scored against them to salvage a 1-1 draw for 10-man Fiorentina.
Spezia moved to eight points above the drop zone after beating 10-man Sampdoria 1-0 in a relegation battle while Torino drew 1-1 with Sassuolo.
Australian Associated Press
