Inter Milan’s lead was cut to one point as they lost 2-1 at home to Lazio, the home team’s Felipe Melo giving away a penalty and being sent off.
Napoli and Fiorentina, in joint second position, both won to close the gap on Inter.
AS Roma eased the pressure on coach Rudi Garcia with their first win in eight games, beating Genoa 2-0. Champions Juventus registered their seventh straight victory, coming from behind to down Carpi 3-2 in the first ever Serie A meeting between the clubs.
Inter have 36 points, Napoli and Fiorentina are on 35 and Juventus 33.