The 10 men of Bologna staged a stunning comeback to deny Inter Milan the chance to move within a point of second-placed Lazio in Serie A.
Musa Barrow struck the winner from inside the box late on, just six minutes after Musa Juwara equalised.
Romelu Lukaku had opened the scoring when he tapped in the rebound after Lautaro Martinez’s header hit the post.
Martinez missed the chance to double his side’s lead from the spot, after Bologna’s Roberto Soriano was sent off.
Both sides finished with 10 men as Alessandro Bastoni was shown a second yellow card with the score poised at 1-1.
Antonio Conte’s Inter remain third in the table, four points behind Lazio, while Bologna move up to ninth.