In the 90 minutes that followed, Paulo Fonseca's Milan, seventh in Serie A, outclassed Real Madrid.
Samuel Chukwueze's 13th-minute strike looked like being the first of a comfortable win but ended up being the winning goal as Milan held on for the points.
Alvaro Morata has been included in Spain's squad for their upcoming Nations League matches.
New AC Milans striker Alvaro Morata was filmed entering his home in Milan by the mayor of the city.
Spain have dazzled on their thrilling run to the Euro 2024 final but just one of their 13 goals in Germany has come from striker and captain Alvaro Morata, who remains a lightning rod for criticism.
After spending over a decade bogged down in disappointment, Spain waltzed their way back to football's peak by reaching Sunday's Euro2024 final in Berlin.
Euro 2024 Semifinal, Spain vs France Highlights: Spain defeat France 2-1 in Euro 2024 semifinal clash on Wednesday.
Spain made a dream start to Euro 2024 as Alvaro Morata scored in a statement 3-0 victory over Croatia in Berlin on Saturday, with Lamine Yamal becoming the youngest player in the competition's history.
Athletic Bilbao arrive in the capital knowing a victory would give them a huge chance of returning to Europe's premier competition for the first time since 2014.
Atletico Madrid had racked up six consecutive league victories before falling short at Estadio de Gran Canaria.