Bologna's veteran Brazilian forward Adailton scored an equaliser deep into injury time to deny Juventus a return to the top of the Serie A table following a 1-1 draw in Turin.
The result left Juventus one point behind leaders Sampdoria, who beat champions Inter Milan 1-0 on Saturday.
They were booed off the San Siro pitch as they slumped to seven points behind Sampdoria after just two wins in six matches and just a solitary goal in their last five encounters.
Juventus coach Ciro Ferrara was furious with his team.
"(The goal) wasn't Bologna's only chance, we were naive and we took too much time to get into position at the back," he said.
"On their goal no-one was there, we gave away too much. I brought in players who hadn't played for a while and maybe we had a problem gelling.
"We need to manage the ball better when we have it and be less frenetic. We need to be more balanced."
If Juve had looked comfortable before the break, they were anything but after it with former striker Marco Di Vaio terrorising their back-line.
He escaped to bear down one-on-one against Gianluigi Buffon but put the ball wide and moments later got free again, rounded the Italy stopper only to see Giorgi Chiellini get back to clear his shot off the line.
Buffon then came to the rescue to keep out a Giacomo Tedesco shot at full stretch before Adailton thrashed the rebound over the bar.
But three minutes into stoppage time Tedesco sent a long, high cross into the box and Adailton arrived at the back post to stab a volley into the ground that bounced up and beyond Buffon's despairing dive.
Just as had been the case in their 0-0 draw at Livorno, Milan had Storari to thank for coming away with a point.
Argentine winger Rivas caused Milan problems and after one mazy run that saw him beat three defenders, including a nutmeg on Alessandro Nesta, he deserved a better finish than hurridly snatching at his shot and blazing over the bar.
Milan, who were largely dominated, had some good chances of their own but the best fell to the recalled Ronaldinho, whose effort looked headed for the top corner until Belgian goalkeeper Jean Francois Gillet intervened.
Italy midfielder Daniele De Rossi salvaged AS Roma coach Claudio Ranieri's unbeaten league start in charge of the giallorosso as his injury-time strike earned a 1-1 draw at Catania following Japan forward Takayuki Morimoto's opener.
Livorno, who lost 1-0 at fourth-placed Fiorentina on Saturday, are the new basement dwellers.
Source: AFP Global Edition