AC Milan defender Simon Kjaer admits defeat to Spezia is difficult to explain.
The loss is a blow to Milan's top four hopes, with the second-leg of their Champions League semifinal against Inter Milan next up.
Kjaer said, "Tonight our performance wasn't enough to get the win, but now we have to think about Tuesday's derby. We have to cancel the today's match, which was in any case fundamental, because there's another war on Tuesday.
"We've had so many difficulties in these matches: it's difficult for me to explain why. Without a doubt, we need to improve our performances.
"With our work we have to be able to erase defeats, the approach must never be lacking. Now we have to raise our heads and work."