The Catalans have lost three of their last four games, including two defeats to Real Madrid in the past week, but Messi is confident they can regain their best form when they need it most against the Italians on Tuesday.
“It is obvious that we have to do a little more. Lately we have come from a run of defeats and we are aware of what we need to do to change that,” he told reporters at a promotional event on Wednesday.
“There is a key game coming up for us to react and make this change.
“To come back is what we all want. We know it will be very difficult, but we believe it’s possible. If they can do it there, then we can do it here.
“We know that if they score a goal it will be more difficult and that Milan have very good players, but we will have our chances.”
Messi also acknowledged that the ongoing absence of coach Tito Vilanova as he undergoes cancer treatment in New York has impacted on the squad, but refused to blame the loss of Vilanova as a reason for their recent dip in form.
“It has affected us a lot and I think it has taken its toll when it comes to preparing for each competition, but we have a strong dressing room and I don’t think we can put the blame on this situation.”