Inter Milan recorded an eighth-successive win in all competitions, but only after struggling to break down relegation-threatened Palermo in a 1-0 victory.
Substitute Joao Mario scored the only goal of the game in the 65th when he was left unmarked to volley home Antonio Candreva's cross.
Both teams were reduced to 10 men late on, with Inter defender Cristian Ansaldi sent off in the 80th for a second yellow card. Inter protested and coach Stefano Pioli was also dismissed.
Palermo midfielder Alessandro Gazzi was also shown a second yellow and sent off in stoppage time.
Inter leapfrogged AC Milan into fifth, a point behind Lazio, although the Rossoneri have a game in hand.