Sassuolo and Fiorentina had to settle for a point each from a thrilling 3-3 draw, while AC Milan and Torino played out a goalless draw.
Cristiano Ronaldo converted a penalty to cap a dominant 3-0 win for Juventus over Fiorentina on Saturday.
Napoli lost further ground on Serie A leaders Juventus after they could only manage a goalless draw at home to bottom club Chievo.
Manchester United could approach Fiorentina to sign defender Nikola Milenkovic in January, according to Sky in Italy.
All the latest transfer news from around Europe, with Real Madrid reportedly interested in Christian Eriksen.
Paulo Dybala scored after 44 seconds for Juventus but they were made to struggle in a 3-1 win over Cagliari on Saturday.
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