Inter claimed a 1-1 Derby d'Italia draw at Juventus and Roma triumphed amid controversy as Serie A began 2015 in entertaining fashion.
Carlos Tevez had looked set to again be the scourge of his former Manchester City coach Roberto Mancini when putting Juve ahead after five minutes, but Mauro Icardi secured Inter a point just after the hour-mark.
Mancini famously rowed with Tevez on the touchline in a 2011-12 UEFA Champions League match against Bayern Munich, and the Argentina international appeared ecstatic to steer Juve into an early lead after fine play by Arturo Vidal.
Icardi levelled with a clever finish in the 64th minute, but Inter's chances of stealing a win ultimately vanished when Mateo Kovacic earned a late red card for a strong tackle on Stephan Lichtsteiner.
Roma moved to within a point of Juve with a highly controversial 1-0 win at Udinese.
Centre-back Davide Astori scored the only goal 17 minutes into the game as he headed Francesco Totti's cross beyond Orestis Karnezis, but the ball did not appear to be completely over the line, with coach Rudi Garcia pleading for the introduction of goal-line technology after the game.
Rafael Benitez's Napoli cruised past Cesena 4-1 to keep themselves level on points with third-placed Lazio, as Jose Callejon, Marek Hamsik and a Gonzalo Higuain double did the damage.
Despite taking an early lead through Andrea Poli, Milan's bid for European football suffered a slight blow as they were beaten 2-1 at home by Sassuolo, with Simone Zaza's fine volley ultimately securing the win after Nicola Sansone's initial equaliser.
Fiorentina's run of five league games without defeat came to a frustrating end as Vincenzo Montella's men lost 1-0 at Parma, who subsequently climbed off the bottom of the table.
Andrea Costa put Parma ahead after 11 minutes and, after Mario Gomez saw his 34th-minute penalty saved by Antonio Mirante, things got even worse for Fiorentina as Gonzalo Rodriguez and Stefan Savic were dismissed in the last 11 minutes.
Palermo made the most of that defeat, moving up to eighth after thrashing 10-man Cagliari – who had Daniele Conti sent off – 5-0 in Gianfranco Zola's first game as the Sardinian club's coach, while Genoa came from two down at home to draw 2-2 with Atalanta.
Empoli and Hellas Verona had Lorenzo Tonelli and Emil Hallfredsson, respectively, sent off during their 0-0 draw, while Torino were held to the same score at Chievo.