Kaka scored his 100th goal for AC Milan on Monday to help it to a much-needed 3-0 win over Atalanta in Serie A, and Napoli beat Sampdoria 2-0 to close the gap on second-place Roma.
Kaka, who is in his second spell at Milan, scored twice to take his tally to 101 goals for the club. Teenage striker Bryan Cristante scored the third in his first start.
In the early match, Dries Mertens scored twice to help Napoli move two points behind Roma, which lost to Juventus on Sunday.
Also, Luca Toni scored twice as newly-promoted Hellas Verona won 3-1 at Udinese.
In other matches, it was: Parma 3, Torino 1; Catania 2, Bologna 0; and Genoa 2, Sassuolo 0.