AC Milan made it five straight wins in the Serie A with a 4-0 thrashing of Catania on Sunday, while Udinese moved top.
Zlatan Ibrahimovic opened the scoring from the penalty spot at the San Siro after Robinho had been felled by Davide Lanzafame.
The Brazilian attacker doubled the lead for Massimiliano Allegri's men with a sublime finish midway through the first half after being released by his Swedish strike partner.
Francesco Lodi then put through his own net on 69 minutes as he attempted to clear Robinho's goal-bound effort before Gianluca Zambrotta completed the rout moments later when he pounced on a rebound from Alberto Aquilani's free-kick.
Meanwhile, with Juventus' clash at Napoli postponed due to flash flooding and storms, Udinese took advantage to move top with a 2-1 win over Siena.
Dusan Basta needed just two minutes to open the scoring, before the in-form Antonio Di Natale netted his eighth league goal of the campaign to double their lead on 64 minutes.
Midfielder Francesco Bolzoni pulled a goal back for the visitors, but it proved to be no more than a mere consolation.
Lazio are a narrow second to Udinese after Giuseppe Sculli's 85th-minute goal gave them a 1-0 win at home to Parma.
Sculli tapped in the winner to see Lazio onto 21 points, equal with Udinese, who they trail on goal difference.
At the other end of the table, Lecce took a step towards moving out of the relegation zone with a 1-0 victory at Cesena.
Colombian Juan Cuadrado struck in the 56th minute and the visitors held on despite being reduced to 10 men when Luis Muriel was given his marching orders.
Lecce are behind 17th-placed Inter Milan on goal difference.
In other matches, Luca Rigoni's effort handed Chievo a 1-0 win over Fiorentina, while Argentine striker German Denis struck 10 minutes from full-time to help Atalanta to a 1-0 victory against Cagliari.
Inter Milan's trip to Genoa was postponed because of flash flooding, which left at least six people dead in the port city.