Ronaldinho sparkled on his debut but could not prevent AC Milan slumping to a dismal 2-1 home defeat to Serie A newboys Bologna in their opener at the San Siro on Sunday.
It was a poor start for scudetto hopefuls as AS Roma were held 1-1 at home to 10-man Napoli while Jose Mourinho's first game in charge of Inter Milan on Saturday night ended in a 1-1 stalemate at Sampdoria.
But it was in Milan where the real drama took place as Carlo Ancelotti handed debuts to Gianluca Zambrotta and Mathieu Flamini as well as Ronaldinho.
Marco Di Vaio gave the visitors a shock lead on 18 minutes after the ball fell kindly to him in the box.
Just before the half hour mark Zambrotta and Ronaldinho combined but the Brazilian headed the full-back's cross straight at goalkeeper Francesco Antonioli from just six yards out.
Ronaldinho was at the centre of everything that was good for Milan and it was his cross that Massimo Ambrosini headed home to restore parity on 41 minutes.
The Brazilian magician then flicked the ball over the defence for veteran striker Filippo Inzaghi to run onto but after rounding Antonioli he couldn't turn his shot from a tight angle inside the post.
After the break it was a similar story with Ronaldinho teeing up Inzaghi and then second-half substitute Andrei Shevchenko, back from a two-year nightmare at Chelsea, but neither could beat Antonioli.
And Francesco Valiani won it for Bologna 11 minutes from time with a thunderbolt from 25 yards out into the top righthand corner.
Ancelotti claimed his team had merely been unlucky. "I'm optimistic, we were unlucky. It was a strange and unusual match but I think they are the surprise of the day," he said. "I don't think we were missing much in the team, we attacked for 90 minutes and were punished by the two chances Bologna had.
"We could have been more compact and together but from a physical perspective we couldn't have done any more than that."
Roma were no less disappointing than Milan as they were held by a team that played more than half an hour with 10 men.
The hosts went in front when Alberto Aquilani ran onto a delicate chip over the defence from Daniele De Rossi and took the ball down on his chest before firing home.
Despite having Fabian Santacroce sent off on 54 minutes, Napoli were level soon after through Slovakia midfielder Marek Hamsik.
Roma's Brazilian goalkeeper Doni then had to make several smart saves to keep the scores level before new-signing Jeremy Menez of France had a double opportunity to win it for the hosts late on but fluffed his lines.
On Saturday, Zlatan Ibrahimovic gave Inter a first half lead in Genoa but Samp fought back after the break to earn a point through Gennaro Delvecchio.
Mourinho didn't seem too upset after the game, though. "The result was fair because we weren't able to close out the match but a draw at a difficult ground is not a big drama," he said. "I'm not super happy but the team didn't play badly."
Lazio are the early pacesetters as they came from behind to win 4-1 at 10-man Cagliari.
Torino are also off to a fine start with a 3-0 home victory against newly-promoted Lecce while Chievo marked their return to the top flight with a 2-1 success over Reggina.
Fiorentina host Juventus in the clash of the day in Florence later on Sunday evening.