ROME, Aug 31 (Reuters) - Francesco Valiani scored a stunning goal for promoted Bologna to beat AC Milan 2-1 at the San Siro on Sunday and spoil Ronaldinho's Serie A debut. Midfielder Valiani blasted the ball home from outside the box in the 79th minute after Massimo Ambrosini had cancelled out Marco Di Vaio's goal for Bologna in the first half. Last year's runners-up AS Roma drew 1-1 with Napoli, who had defender Fabiano Santacroce sent off for a second yellow card in the 54th minute. Champions Inter Milan were held 1-1 at Sampdoria on Saturday in new coach Jose Mourinho's league debut, while Juventus kick off their campaign at fierce rivals Fiorentina later on Sunday. Former Italy forward Di Vaio, a close-season signing from Genoa, dented the San Siro's excitement at Ronaldinho's debut in the 18th minute with a fine diagonal strike. The Brazilian had a hand in the equaliser, floating a cross into the area four minutes before the break for Ambrosini to head home. Ronaldinho went on to create a string of chances that his team mates failed to put away. One fell to Andriy Shevchenko, who could not find the net with only the keeper to beat at the start of the second half after coming off the bench to mark his return to Milan after two troubled seasons at Chelsea. 'Early season surprises can happen when teams that aren't in top condition meet better prepared sides, like Bologna today,' Milan coach Carlo Ancelotti said. 'The impression I had is that this team can do excellent things, perhaps by changing something, maybe the system of play. My optimism derives, above all, from Ronaldinho's performance.' At Rome's Stadio Olimpico, Alberto Aquilani nudged the ball home for the hosts just before the half hour after fellow Italy midfielder Daniele De Rossi had picked him out in the area. Marek Hamsik knocked in the rebound of his own header on to the crossbar to level for Napoli shortly after Santacroce's sending off. In Sunday's other matches, Torino beat Lecce 3-0 in Turin, Lazio came from behind to beat 10-man Cagliari 4-1 in Sardinia, Atalanta and Catania secured 1-0 home wins over Siena and Genoa, and Chievo beat Reggina 2-1 in Verona. Those teams join Bologna and Udinese, who beat Palermo 3-1 in their opening game on Saturday, at the top of Serie A. Pavel Nedved scored for Juventus in the 39th minute after his Czech compatriot Zdenek Grygera burst into the box from the right and served an inviting pass from the baseline. Striker Alberto Gilardino, a close-season signing from AC Milan, earned Fiorentina a draw at the death when he spun away from Olof Mellberg and crashed the ball home. Fiorentina had Felipe Melo sent off shortly before Gilardino's equalizer for a bad tackle on Juve's Cristian Poulsen.