Promoted Bari stunned struggling giants Juventus 3-1 late Saturday with goals from Riccardo Meggiorini, Brazilian Paulo Barreto and former Juve's Argentine Sergio Almiron, dpa reported.
Juve continued their inconstant and disappointing season inflicting their fans with yet another frustrating show after last week's encouraging 2-1 win over leaders Inter Milan was followed by a 4-1 debacle against Bayern Munich.
Troubled began early for the Turin guests as striker Meggiorini on seven minutes topped with his goal a brisk start from the solid hosts.
The striker had some luck when a tackle with Claudio Marchisio resulted in an inviting drooping ball that he volleyed past Gianluigi Buffon as a deflection from defender Nicola Legrottaglie wrong-footed the goalkeeper.
After a few minutes on the ropes, Juve began crunching offensive actions, with Brazilian Amauri on 18 minutes firing wide from few metres away after a deep pass-and-go with Marchisio.
There was more trouble for Buffon on 22 minutes, as defender Leonardo Bonucci nodded high with the Juventus defence dithering, as they often do, on a dead-ball situation.
One minute later, however, Frenchman David Trezeguet equalized with a simple flick after Jean-Francois Gillet nicked a nasty low drive from Brazil play maker Diego.
Trezeguet's striking mate Amauri had a weak close-range flick blocked before Bari regained the lead through a controversial spot kick awarded when Fabio Cannavaro tackled Paulo Barreto, who rose to convert past Buffon on 44 minutes.
Bari's fast counter attacks were a serious threat for Juve after the break, but there were good chances when Trezeguet's close-range volley found Gillet in the right spot to deflect.
Portugal's Tiago volleyed wide as he pounced on an loose ball, then botched an inviting cross from Diego on 65 minutes and Legrottaglie missed by a hairsbreadth when he nodded a corner kick on 75.
Buffon rescued his static defence on 66 minutes, grabbing a header from Meggiorini, while Diego embodied his side's troubles when he badly botched a spot kick after Almiron floored the just fielded Fabio Grosso.
With nine to go, Almiron found the far corner from the distance to seal Juve's defeat.
Ciro Ferrara's side remained in third position five points adrift of Inter, while Bari moved up to share the fifth position with five other teams.
Cagliari and guests Napoli drew 3-3 earlier Saturday in a thrilling game that saw the Sardinia hosts rally from two down before Mariano Bogliacino levelled with a last-gasp header.
Inter are away to lowly Atalanta Sunday, when second-place AC Milan, trailing four points behind, host Palermo.