AC Milan coach Stefano Pioli admits his players are at a low ebb after their humiliation by Sassuolo.
Sassuolo hit five goals at San Siro stadium to thrash the champions on Sunday.
Pioli said: "It is a tough defeat, the moment is difficult. We must react: after the failure to win with Roma we got lost, we have many tactical and mental difficulties. We must not stop believing in our abilities, but we need to work with more attention and precision, because our play will have to go up a level.
"There are two factors: mental and tactical. I have to get even more into the players' heads, understand what it takes to get out of this moment, and I also have to understand how to make tactical changes.
"It is not three or four defeats that make me change my mind about my group, or about my players' sense of responsibility. If we need to talk to each other even more directly we will do it. None of us wanted to play such a negative game, this must encourage us not to repeat certain performances anymore, also taking advantage of a great game: the higher the peak to climb, the greater the satisfaction of achieving certain goals."