It is true that Liverpool is not as strong as they have been in recent years, but Milan is currently very weak and have taken 5 points from 4 games in Serie A, which is very bad indeed. Liverpool have won 3 out of 4 games in the PL and in my opinion they are the favourites in this match and I don't see any chance for Milan to be honest.
The match is going to be an interesting and difficult one for the two clubs, I know Ac Milan shouldn’t be underestimated, but I still think Liverpool should be able to win the match. I know most people are going to use Liverpool's last Premier League match to judge, i will say the match result came as a surprise to me because I never expected Liverpool to lose the match, but that doesn’t mean they will perform poorly when playing against Ac Milan in the Champions League. Liverpool's performances have not really been bad this season, four matches which they have played, at least they performed well in three matches, so I am expecting a win from Liverpool in the match.