The two sides meet tomorrow night in the Champions League with the Catalans heavy favourites to progress.
“There is a big difference between Barcelona and Milan, the difference is in favour of Barca,” said Sacchi.
“Of course the Catalans are favourites, but in a Champions League game, if you are not 100 per cent focused, you can run into many pitfalls.
“Barca are harmonious, modern and attractive, they illuminate every game. Xavi Hernandez’ return to fitness is important, as besides being a great player he is the most important, the true leader, for the style of play.
“It will be a great match between two teams with great history and a charm. Barca are in a fantastic moment, but Milan are experiencing one of their better moments and they are always a tough opponent to deal with.”