Napoli failed to make up ground on Serie A leaders Juventus on Sunday, instead settling for a 1-1 draw with Fiorentina at the Stadio Artemio Franchi.
The Bianconeri banished talk of a crisis by dispatching Udinese 4-0 on Saturday night, with Paul Pogba netting twice, but Napoli could not repeat the trick at the Stadio Artemio Franchi.
Facundo Roncaglia's spectacular, if unintentional, goal from within his own half gave the home side the lead in the 33rd minute, but Edinson Cavani replied within 10 minutes to join an exclusive club of players with 100 Serie A goals.
Giampaolo Pazzini fired AC Milan above Roma and into sixth place in the table with a well-taken brace in a 2-1 win. There was a touch of fortune about his opener deep into the second half, but his second goal was borne of fantastic individual skill and a predatory instinct in front of goal.
Philippe Mexes gave the hosts cause for concern with a careless own goal in the final stages but a rejuvenated Milan side found themselves back in the race for Europe.
Roma's later bid to claim sixth place back from Milan failed as the Giallorossi were held to a frustrating 1-1 draw by Inter Milan. Francesco Totti's penalty put Roma in front in the 22nd minute before Rodrigo Palacio equalised in first-half stoppage time.
Catania's bid to take European football to Sicily continued apace thanks to a 2-0 victory at relegation-threatened Genoa, whose head coach's future is hanging in the balance. The Sicilian club closed to within two points of a Europa League berth as Genoa failed to respond to goals in either half from Gonzalo Bergessio and Pablo Barrientos.
Reports in Italy suggest Luigi Del Neri, who replaced Luigi De Canio in October, risks losing his job with Genoa currently cast three points adrift of 17th place and safety.
Elsewhere, Chievo restricted Parma to a frustrating 1-1 draw at the Stadio Marc'Antonio Bentegodi that did nothing to boost either side's ambitions.
Roberto Donadoni's men took the lead against the run of play, Ishak Belfodil scoring from Parma's first attack immediately before the break but Alberto Paloschi ensured the points were shared with a headed goal shortly before the hour mark.
The start of Atalanta's home game with Cagliari had been delayed by 30 minutes due to heavy snow but the points were shared as Guglielmo Stendardo cancelled out Michele Canini's own goal before Luigi Giorgi saw red late on.
Bottom club Siena recorded a first league win in seven games when Erjon Bogdani settled a 1-0 victory over Sampdoria, while Pescara lost 2-0 at home to Torino thanks to goals from Mario Santana and Alessio Cerci.