Milan's title dream was quickly dashed as Lazio won 1-0 thanks to a goal from Gustav Isaksen, while Rafael Leao reacted angrily after being substituted.
After winning the "Derby della Madonnina" and Inter drawing with Atalanta, Milan had the opportunity to move closer to the title race.
Ardon Jashari played in midfield due to absences, while Lazio was also supported by the return of fans to the "Stadio Olimpico".
The match had chances for both teams, but the decisive moment came when Isaksen took advantage of a long ball from Adam Marusic and scored for Lazio, beating Mike Maignan, in the first half.
Milan tried to react in the second half with several chances and shots on goal, but failed to equalize.
In the end, Lazio maintained the advantage and took an important victory that dealt a blow to Milan's Scudetto hopes.
Milan now remain eight points behind Inter in the title race, with the Rossoneri having 60 points, while Inter have 68./Express newspaper/