Milan were thrashed 4-0 last night in the second-leg of their Champions League tie.
"I knew it was going to go badly yesterday afternoon. We had taken Alexandre Pato, Alessandro Nesta and Luca Antonini in the squad, but all three of them pulled out with injuries on Tuesday," he said of the 4-0 defeat at Old Trafford.
"Without such important players and taking on a Manchester United side of such quality, it was always going to be extremely difficult.
"I don't think it will affect our Serie A form. Leonardo already did very well in the locker room to reassure the players."