#2 Alisson's absence in front of the goal
Alisson Becker sustained an injury in the Premier League game against Norwich. His absence might not be very noticeable on paper. With Virgil van Dijk marshaling the defense, Joe Gomez alongside and Andrew Robertson and Trent Alexander-Arnold in the flanks and with Fabinho, Jordan Henderson and James Milner, all very capable in their defensive duties, Liverpool is a strong side at the back.
However, it isn't like teams don't get shots at them. Tottenham had a lot of shots on goal in the UCL final but they were denied for the grit of one man, Alisson. The Brazilian has also come up with important saves in a lot of other games.
Against Manchester United, Chelsea did get chances and they didn't capitalize on it. Emerson got a lot of shots which were parried away by David de Gea. Alisson might deal with dangerous shots but his replacement Adrian is a name hardly anyone has heard and is 32. The emergency backup keeper Andy Lonergan is 35.
Van Dijk has shown confidence in the backup keeper Adrian with but it's still a massive change from Alisson. No matter how much the Anfield faithful or van Dijk try to downplay this injury, Alisson is among the top three 'keepers in the world.