Milan's 2-1 away defeat on the first weekend of the campaign was a jolt to Massimiliano Allegri's team, but they responded in the right way seven days down the line at the San Siro.
Robinho put Milan in front after eight minutes, Philippe Mexes added a second on the half-hour mark and Mario Balotelli netted the third after 62 minutes.
Shortly after Mexes scored, Cagliari reduced their deficit through Marco Sau but they were finished off by Balotelli, who also had a hand in the opening two goals from the home side.
Inter Milan continue to show signs of revival under new coach Walter Mazzarri after cruising to an impressive 3-0 win at Catania.
The Nerazzurri finished a dismal ninth last season but, under the supervision of former Napoli boss Mazzarri, claimed a regulation victory over Genoa on the opening day of the new campaign.
Rodrigo Palacio and Yuto Nagatomo, who both scored last weekend, were on target again at the Stadio Angelo Massimino while Ricky Alvarez cemented a result which would have been off limits to the Inter side of six months ago.
Giuseppe Rossi and Mario Gomez both scored doubles for Fiorentina in their 5-2 win at Genoa, after Alberto Aquilani grabbed the opener. Alberto Gilardino and Francesco Lodi replied for the well-beaten home side. Lodi's goal, like Gomez's second in the last minute, was a penalty.
Roma overcame Verona 3-0 with second-half goals from Miralem Pjanic and Adem Ljajic, and an own goal from Fabrizio Cacciatore.
Atalanta beat Torino 2-0 with goals from Guglielmo Stendardo and Stefano Lucchini, and Udinese toppled Parma 3-1, their goals coming from Emmanuel Agyemang-Badu, Thomas Heurtaux and a late Luis Muriel penalty. Antonio Cassano scored Parma's goal.
Livorno enjoyed their trip to face Sassuolo, emerging 4-1 winners.
They went ahead shortly before half-time through Leandro Greco, were pegged back in the 66th minute by Simone Zaza, but then seized control as two goals from Innocent Emeghara, the second a penalty, and one from Paulinho, gave them the resounding margin of victory.
Bologna were held 2-2 at home by Sampdoria. The hosts' goals came from Davide Moscardelli and Panagiotis Kone, with Eder and Manolo Gabbiadini on target for Samp.
Sunday's Serie A Results