AC Milan also triumphed in the late game, the returning David Beckham producing a good all-round display in front of England coach Fabio Capello in a crushing 5-2 home win over Genoa.
Giuseppe Sculli's header gave Genoa the lead midway through the first half after Ronaldinho had a penalty saved but the Brazilian showed courage to slot in another spotkick to equalise when the rampant Massimo Ambrosini was again tripped.
Thiago Silva, Marco Borriello's classy second-half double and a Klaas-Jan Huntelaar penalty completed the rout for second-placed Milan, who had to start on-loan Beckham on the right of a front three because of Alexandre Pato's injury.
Milan, who let Genoa debutant David Suazo net late on, stayed eight points behind Inter with a game in hand and visit Juve on Sunday.
Champions Inter scored on 12 minutes when Mario Balotelli's shot was cleared from the line and new signing Goran Pandev nodded home, only for replays to show Balotelli's effort was in.
Striker Pandev had not played a league game since May having been banished from the Lazio squad in a contract dispute but made an immediate start because of injuries, suspensions and Cameroon's Samuel Eto'o being at the African Nations Cup.
The Macedonian belied his lack of sharpness with a lively display as Inter clung on and avoided conceding a late penalty for a Ricardo Quaresma handball.
Cristian Chivu suffered a fractured skull and Patrick Vieira shone in probably his last Inter game.
"Patrick has found the best way to say goodbye," coach Jose Mourinho told Sky, adding he did not know his destination.
"I'm super satisfied. These are the matches that decide lots. What makes the difference is personality and character."
CACERES DISMISSED
Juventus had lost three in a row in all competitions before the mid-season break, prompting media speculation that Russia coach Guus Hiddink was being lined up to replace Ciro Ferrara.
Right winger Hasan Salihamidzic was brought into a new 4-4-2 formation and headed the visitors in front on three minutes before former Juve striker Nicola Amoruso equalised for Parma.
Paolo Castellini nodded a corner into his own net to give third-placed Juve the lead again on 39 minutes and Ferrara's men held on despite having Martin Caceres dismissed for two yellows.
Napoli went fourth after a 2-0 win at lowly Atalanta while fifth-placed AS Roma conceded twice in stoppage-time in a 2-2 draw at Cagliari where new striker Luca Toni came off the bench.
Fiorentina got back to winning ways with a 5-1 thrashing of bottom side Siena.
Sampdoria and Palermo drew 1-1.
At the bottom, Sergio Floccari netted twice on his Lazio debut in a 4-1 victory over Livorno and Sinisa Mihajlovic's Catania beat his former side
