Serie A champions Inter Milan were surprisingly held 1-1 by newly-promoted Bari in their opening match of the new season.
Samuel Eto'o, who joined Inter from Barcelona this summer in the deal that took Zlatan Ibrahimovic to Spain, handed his side the lead on 55 minutes via the penalty spot.
Former Bayern Munich defender Lucio also made his league debut for the Italian giants but he was unable to keep a clean sheet as the unthinkable happened.
With 17 minutes remaining, Bari dug deep and stunned the Stadio Giuseppe Meazza when striker Vitali Kutuzov slotted home.
Genoa are the surprise early leaders after they recorded a shock 3-2 victory over Roma at Stadio Luigi Ferraris.
Substitute Domenico Criscito opened the scoring for the home side before Roma turned the game on its head via goals from Rodrigo Taddei and Francesco Totti.
But Genoa were not to be beaten as Alberto Zapater equalised before Giuseppe Biava bagged a late winner.
Juventus got their campaign off to a winning start with a 1-0 home victory over Chievo.
Striker Vincenzo Iaquinta fired home the only goal of the game, netting in the 11th minute.
Udinese and Parma played out a four-goal thriller at the Stadio Friuli.
Alberto Paloschi put away team Parma in front but Antonio Di Natale restored parity from the penalty spot.
Alessandro Lucarelli then scored four minutes into the second half and looked to have handed Parma the spoils only for Di Natale to level in the 90th minute.
Lazio were the victors in their clash against Atalanta as Tommaso Rocchi's 22nd minute goal proved decisive.
Fabrizio Miccoli was the hero for Palermo as the home side recorded a 2-1 victory over Napoli.
Marek Hamsik was on hand to cancel out Edinson Cavani's opener before Miccoli bagged the winning goal.
A last minute goal from Daniele Gastaldello ensured Sampdoria snatched a late 2-1 win at Catania.
Giampaolo Pazzini got Sampdoria up and running but Takayuki Morimoto levelled before Augustyn Blazej was handed a red card.
And Sampdoria made their numerical advantage pay as Gastaldello struck in the dying moments to ensure three points.
Elsewhere, Livorno and Cagliari played out a goalless stalemate at Stadio Armando Picchi.