New Inter boss Leonardo made a successful start as his side recorded a 3-1 victory over Napoli.
• Moratti hails Leonardo impact
Thiago Motta was the hero for the home side with the first and the last goal in a pulsating game. He put Inter ahead after three minutes, but Michele Pazienza deservedly levelled for an impressive Napoli in the 25th minute.
Esteban Cambiasso restored Inter's lead in the 37th minute before Motta's second sealed the win and allowed Inter to start eating into their huge deficit on league leaders AC Milan.
Parma made a fine start to 2011 with a 4-1 win over ten-man Juventus in Turin.
Juve had Felipe Melo sent off in the 17th minute and missed the chance to temporarily go second in the table.
They held out until the 41st minute, but Sebastian Giovinco scored either side of the break and, while Juve's Nicola Legrottaglie reduced the arrears on the hour mark, Hernan Crespo restored Parma's two-goal lead two minutes later and substitute Raffaele Palladino capped a wonderful afternoon for Parma by making it 4-1 with seconds remaining.
Substitute Sidney Strasser netted his first professional goal five minutes from time at Cagliari to give AC Milan a 1-0 win that moved them five points clear at the Serie A summit.
Strasser, a 20-year-old Sierra Leone midfielder, slotted home a late winner after fine work from new signing Antonio Cassano.
The result extended the Rossoneri's advantage at the top to five points over second-placed Lazio, who played out a 0-0 draw with Genoa at the Stadio Luigi Ferraris.
In a game which lacked clear-cut goalscoring chances, the closest either side came to breaking the deadlock was when Lazio forward Hernanes hit the post early in the second half.
Roma came from behind to beat Catania 4-2 at the Stadio Olimpico and maintain their seven-point gap to runaway league leaders AC Milan.
With the game looking to be heading for a 2-2 draw with four minutes remaining, second-half substitute Mirko Vucinic came to the rescue by scoring twice to fire Roma to victory.
Marco Borriello had given the hosts a fifth-minute lead before Catania's Matias Silvestre equalised before the half-hour mark. Maxi Lopez put the Sicilians in front in the 38th minute but Borriello made it 2-2 shortly after the restart.
Palermo boosted their pursuit of a European place with a comfortable 3-0 win over a Sampdoria side who were punished for their wasteful finishing. Goals from Fabrizio Miccoli in the first half and Giulio Migliaccio and Massimo Maccarone in the second made for a one-sided scoreline.
Mario Santana came off the bench to salvage a 1-1 draw for Fiorentina at fellow Serie A strugglers Bologna.
Marco di Vaio had put the hosts in front in the fifth minute at the Stadio Renato Dall' Ara but Santana saved his team from defeat by grabbing the equaliser midway through the second half.
Two atrocious defensive errors in the first half saw Brescia beaten 2-1 at home by fellow strugglers Cesena.
Jonathan Zebina gifted the opening goal to Luis Jimenez and Luca Ceccarelli took advantage of more hesitant defending to put the visitors in control at the break. Citadin Eder scored four minutes after half-time to ensure the match remained a contest but Brescia were unable to find an equaliser as Cesena held on comfortably.
Ten-man Udinese claimed their sixth home win of the campaign with a dominant 2-0 win against Chievo. Alexis Sanchez put the hosts in front in the 14th minute and Antonio Di Natale doubled Udinese's lead shortly afterwards.
Serie A's bottom club Bari made the perfect start to 2011 as debutant Stefano Okaka struck a late winner to secure his side's first away win of the season in a 1-0 victory over Lecce. The Galetti move within a point of their second-bottom hosts.