Inter Milan's Serie A title hopes took a blow after they were beaten 1-0 by Bologna thanks to Riccardo Orsolini's last-gasp strike.
Inter got off to a bright start in the opening stages but the hosts soon took control and had opportunities to take the lead through Dan Ndoye and Juan Miranda.
Carlos Augusto and Joaquin Correa had two promising chances either side of the break, but the game looked destined to finish as a goalless stalemate until Orsolini struck at the end with a stunning volley.
Defeat means Inter remain top of the table only on goal difference after second-placed Napoli beat Monza on Saturday to move level on 71 points with five games to go, while victory sees Bologna move into the top four.
Inter boss Inzaghi made two changes to the team which drew 2-2 with Bayern Munich in midweek to secure a spot in the Champions League semi-finals as Augusto and Correa both came into the starting line-up.
The visitors had two chances in the opening stages of the match when Federico Ravaglia made an early save from Lautaro Martinez and Augusto nodded narrowly wide of the upright.
However, Bologna began to take charge when Miranda's shot flew over the crossbar and Ndoye came close moments later, but sent his strike wide before having another effort from distance just miss the target.
They continued to threaten when Miranda smashed the ball over the bar and Inter goalkeeper Yann Sommer was called into action to deny Michel Aebischer before Thijs Dallinga had a menacing strike blocked by Benjamin Pavard.
Inter had a chance moments later when Augusto headed wide from Hakan Calhanoglu's cross and the midfielder continued to create chances, whipping another dangerous ball into the box, but Alessandro Bastoni nodded over the bar.
The visitors aimed to build on their strong finish to the first half when Correa came close just after the break but Bologna nearly broke the deadlock moments later when Benjamin Dominguez curled an effort just past the post.
A scrappy second-half display saw both sides struggle to find themselves in goalscoring positions until the final 15 minutes, where Federico Dimarco floated in a promising ball for Augusto, whose header flashed wide.
A surge from Bologna saw Miranda and Nicolo Cambiaghi have shots on target before Sommer made a save from Emil Holm's strike in the 90th minute.
Orsolini then had the final say in the fourth minute of stoppage-time with an incredible finish on the volley stemming from Miranda's long throw-in, with his 12th league goal of the season snatching victory for the hosts.
