Juventus missed the chance to reclaim an eight-point lead at the top of Serie A after suffering a shock 2-1 home loss to 10-man Sampdoria, while Inter Milan suffered a defeat at Udinese.
Having finished 2012 with a record haul of 94 points, Juve boss Antonio Conte was backing a concerted bid to outstrip that achievement this year, and Sebastian Giovinco's early penalty put his side on the right path.
Juve's task looked easier when Gaetano Berardi saw red for two first-half bookings but the numerical advantage did little to help the hosts, as Mauro Icardi levelled the scores shortly after the break.
Icardi completed his brace with what proved to be the winner, his sensational strike rattling the Bianconeri to condemn them to a second home defeat of the season, also earning Delio Rossi a first victory as Samp boss.
And with second-placed Lazio beating Cagliari on Saturday, Juventus now lead the standings by just five points ahead of a daunting trip to Parma.
A second-half salvo earned Udinese all three points with a 3-0 win over the 10 men of Inter Milan at the Stadio Friuli.
Antonio Di Natale was on target twice with Luis Muriel also scoring for Francesco Guidolin's side, who were aided by a red card for Juan Jesus in the 65th minute.
The win lifts Udinese up to eighth in the table, level on points with AC Milan, who have a game in hand, while Inter slip to fifth.
AC Milan further reduced the gap on the top six thanks to a 2-1 win over Siena at the San Siro.
Second-half goals from Bojan Krkic and Giampaolo Pazzini earned the Rossoneri the points with Michele Paolucci scoring a late consolation for the Tuscans, who remain rooted to the foot of the table, six points adrift of safety.
Napoli's Edinson Cavani demonstrated why he is fast becoming the envy of a host of top European clubs with an exquisite hat-trick to down 10-man Roma 4-1.
Napoli were desperate to atone for a woeful end to 2012 that saw the Serie A challengers slip 10 points away from league leaders Juventus, courtesy of both consecutive defeats and disciplinary sanctions.
Zdenek Zeman's Roma are eager to keep pace with the chasing pack but identical goals from Cavani at the start of either half caught the Giallorossi unawares, with the Uruguay international soon making it eight goals from 11 appearances against the capital club to put the result within reach.
Substitute Pablo Osvaldo offered shellshocked Roma a glimmer of hope with a consummate finish in the 73rd minute, but Miralem Pjanic's dismissal left room for one last goal from Christian Maggio and Napoli duly returned to third place in the table.
Pescara eased their relegation worries with a stunning upset of Champions League hopefuls Fiorentina 2-0 in Florence.
Pescara were indebted to goalkeeper Mattia Perin as they survived a first-half onslaught before snatching victory through second-half goals from Jonathas and Mervan Celik.
It meant Fiorentina missed the chance to move within a point of second placed Lazio and they were overtaken by Napoli.
A last-gasp goal from substitute Amauri condemned his former club Palermo to another defeat, 2-1 at Parma, as the Gialloblu claimed a third consecutive victory.
Parma survived their visitors' early enthusiasm to snatch the lead through Ishak Belfodil midway through the second half but Igor Budan pegged his former employers back with an equalising header.
There were half-chances for Gian Piero Gasperini's men to edge a first win in Parma since their promotion in 2004, but Brazilian striker Amauri ensured they went home empty-handed with a confident finish three minutes into stoppage-time.
Isaac Cofie's first goal for Chievo settled a narrow 1-0 victory over Atalanta that keeps the Gialloblu in the hunt for a top-half finish.
The Flying Donkeys were denied an historic fourth straight win by Torino in the last game of 2012, but Ghana international Cofie ensured a fourth win from five outings with his powerful strike shortly before half-time.
Atalanta, meanwhile, slip below their hosts and into 12th place after suffering their fifth defeat from seven games, despite the best efforts of strikers Giuseppe De Luca and German Denis on the counter-attack.
Marco Borriello struck a second-half brace to help Genoa down fellow strugglers Bologna 2-0 and claim only their fourth win of the season.
Borriello opened the scoring in the 57th minute after linking up well with Ciro Immobile before the much-travelled striker sealed the points with a fine finish in the 73rd minute.
The victory lifts Genoa out of the relegation zone and they are now just one spot and one point below 16th-placed Bologna, whose miserable afternoon was made complete when they saw midfielder Tiberio Guarente sent off in stoppage time.
Information from the Press Association was used in this report