Serie A title hopefuls Napoli suffered their first defeat since the opening day of the season when they were stunned 3-2 at Roberto Donadoni's resurgent Bologna on Sunday.
Mattia Destro, revitalised since the new coach was appointed, scored in each half for Bolgna, either side of a Luca Rossettini header.
While Gonzalo Higuain scored two late goals to set up a dramatic finale, Bologna held on to secure one of the unlikeliest results of the season and raise doubt about Napoli's title credentials.
Napoli remain second on 31 points, missing the chance to retake top spot from Inter Milan, who beat Genoa 1-0 on Saturday, while victory takes Bologna out of the relegation zone and up to 15th on 16 points.
Maurizio Sarri's side headed into this match with Serie A's joint-best defensive record, having conceded only nine goals, and their superb backline had underpinned an 18-game undefeated streak in all competitions, stretching back to an opening-day loss at Sassuolo.
Bologna, though, have lost only once since Donadoni replaced Delio Rossi at the end of October and started strongly, taking the lead in the 14th minute.
Destro, who moved to Bologna from Roma during the summer, was picked out by a long ball from Amadou Diawara, and outmuscled Raul Albiol before slamming the ball past Pepe Reina for his third goal of the season.
Rossettini extended the advantage seven minutes later when he headed Franco Brienza's pinpoint corner past Reina, before the Spanish keeper let a first-time Destro shot slip past him on the hour mark after lax defending by the visitors.
Higuain revived Napoli when he pulled a goal back in the 87th minute after touching a Lorenzo Insigne cross past Mirante, and added another three minutes later with a low strike to set up a tense finale.
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