The Portuguese coach spoke to Sky Sport 24 after AC Milan suffered another Europa League setback at San Siro, with the defeat marking their third loss in four matches in the competition.
Amorim struggled to find an explanation for what he had witnessed, particularly during the opening 45 minutes, and pointed to a lack of ambition and concentration within his team.
“There is no explanation. There is nothing I can say, especially about the first half. I don't remember another first half like that.
“It is about ambition, concentration, ambition. We gave away opportunities, we made stupid gifts. We were not prepared to play football tonight.”
The blunt assessment reflected the coach's frustration with a performance in which Milan had failed to meet the demands of the occasion.
Amorim offered little by way of consolation or tactical explanation, instead making clear that the players' preparation and mentality had fallen short of what was required.
His comments followed a difficult European campaign for Milan, who had now lost three of their opening four matches in the competition.