Neither side could find the net in the Milan derby, while Roma missed the chance to go second.
Napoli are within five points of Roma and a Champions League place after a comfortable 3-0 Serie A victory at Cagliari.
Marek Hamsik scored twice as Napoli took a giant step towards the Europa League semi-finals by beating Wolfsburg 4-1 away.
Napoli shrugged off the disappointment of a disallowed ghost goal to push on and beat Fiorentina 3-0.
Sinisa Mihajlovic has given no clues about his future as Sampdoria coach with AC Milan and Napoli rumoured to be interested.
Napoli have insisted they want Rafael Benitez to remain as manager despite the Spaniard rejecting a three-year contract.
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