Early goals from Francesco Acerbi and Lautaro Martinez proved insufficient for Inter Milan as Bologna snatched a 2-2 draw at the San Siro in Serie A on Saturday.
Inter took the lead when Acerbi scored a goal 11 minutes in, evading his marker and nodding in a header from a corner, with Martinez doubling the advantage two minutes later with a powerful strike from outside the box.
Bologna reduced the deficit 19 minutes in as Riccardo Orsolini converted a penalty following a VAR review that confirmed Martinez had pulled Lewis Ferguson's shirt.
Seven minutes into the second half, Joshua Zirkzee completed the comeback with a shot from the edge of the box that deceived Inter's goalkeeper Yann Sommer and found the bottom corner of the net.
Inter are top of the table with 19 points, one ahead of AC Milan, who play at Genoa later on Saturday. Bologna are in eighth place.