AC Milan extended their lead to five points in the Serie A title race after they picked up a 1-0 win at Cagliari on Thursday.
Juventus began their 2011 on a sour note at home and immediately lost pace in the title race after receiving a sound 4-1 beating at the hands of Parma at home, with Brazilian midfielder Felipe Melo's straight red card in the 17th minute the catalyst.
Melo was dismissed for lashing out with his boot and catching Massimo Paci in the face while the duo tangled on the ground.
It was a familiar face who put Parma in front, with diminutive attacker Sebastian Giovinco - on-loan at the vistors from Juve - putting his side ahead after 41 minutes.
Giovinco rubbed salt in the wound of his parent club by doubling Parma's advantage just seven minutes later, having been set up by experienced striker Francesco Valiani.
Veteran defender Nicola Legrottaglie pulled a goal back for Juve on 60 minutes, but further strikes to Hernan Crespo and substitute Raffaele Palladino completed Parma's rout.
Juventus slip to fifth on the table, with Roma overtaking them courtesy of a 4-2 win over Catania. Marco Borriello and Mirko Vucinic both claimed doubles for the victors.
League leaders Milan chalked up a 1-0 win away to Cagliari thanks to an 85th-minute strike from 20-year-old substitute Rodney Strasser, while title rivals Lazio were held 0-0 away to Genoa.
Inter Milan picked up their pace under new coach Leonardo with a 3-1 win over Napoli.
Thiago Motta ensured a dream start for the Brazilian coach with a third-minute opener, although Michele Pazienza dampened the mood when he equalised 22 minutes later.
But Esteban Cambiasso restored the home side's lead eight minutes before the break and Motta's second 10 minutes after it wrapped things up.
Brescia lost 2-1 at home to Cesena, ensuring the winners jumped out of the relegation zone at the losers' expense.
Udinese triumphed over Chievo 2-0, while Palermo chalked a 3-0 win over Sampdoria.
Bologna and Fiorentina could not be split at 1-1, while bottom-placed Bari breathed hope into their bid to escape relegation when Stefano Okaka's 77th-minute strike handed them a crucial 1-0 away win at fellow strugglers Lecce.