AC Milan missed the leap to the top of the Serie A table.
In the city duel with defending champion Inter, the football team of coach Stefano Pioli only scored 1-1 (1: 1) and could not use the mistake of the table leaders SSC Napoli with the same points on Sunday evening.
Napoli had previously only played 1-1 against Hellas Verona.
AC Milan were twice as lucky in the draw.
Hakan Calhanoglu (11th minute), who had played for Milan for four years, gave Inter the lead with a penalty he inflicted on himself.
But Inter defender Stefan de Vrij (17th) equalized with an own goal.
Ten minutes later, de Vrij's team-mate Lautaro Martinez failed with another penalty kick against AC substitute keeper Ciprian Tatarusanu.
In the closing stages, the AC team missed a few scoring opportunities.
Substitute Alexis Saelemaekers had the best, who hit the post in the 90th minute.