Stephan El Shaarawy's goal was enough to earn AC Milan all three points against Genoa, while Siena and Palermo drew 0-0 on Saturday.
The Italy international decided a tense encounter in the 77th minute, resolving Milan's immediate problems in Serie A, in which they have moved up to ninth, but leaving them still with plenty of margin for improvement.
Genoa lost their second game in a row to fall behind Milan in the table with the managerial switch from Luigi De Canio to Luigi Del Neri having no immediate impact.
With a goalless draw looking increasingly likely, Ignazio Abate was sent through by Urby Emanuelson just to the right of the penalty area in the 77th minute.
The linesman's flag stayed down and the Milan full-back's low cross was met in front of goal by El Shaarawy, who stroked the ball in from five yards.
Strugglers Siena and Palermo played out a goalless draw at the Stadio Artemio Franchi with the result not helping either side out a great deal.
Palermo had the better chances, but were unable to beat a Siena side who, without a six-point penalty, would be ahead of the Rosaneri in the table.
As it is, though, Serse Cosmi's side are still four points adrift of the Sicilians, who also remain in the bottom three having played a game more than the teams above them.
