Inter's 3-1 defeat at Catania last night means Milan can move within a point of the leaders if they beat Chievo.
"At this moment we are still four points off Inter because we haven't won our game yet," warned Leonardo.
"As we have seen from the start of the season to this moment, Serie A is very unpredictable and if we are in this position then we must take advantage of it game after game. All of this has taken us to second place.
"There are 11 rounds to go and I don't think Inter's defeat will be decisive, but it certainly is nice to be closer and lighting the touch paper on this campaign. It's particularly pleasing to be up there after a game like the one we had in Manchester."