1. Liverpool's defensive fragilities
To win the tie over two legs, it is imperative that Atletico Madrid get a respectable result at Anfield. The big teams that have come to Anfield in the past 2 seasons have made the mistake of keeping the ball and allowing the Reds play on the counter. Whereas, Atletico Madrid's natural style is to play on the counter and Diego Simeone would not be looking to change that.
It is safe to say that Liverpool will have the ball at Anfield in the second leg and that might result in a high defensive line once again. If the Los Rojiblancos will be able to win the ball in midfield, they have players like Joao Felix, Deigo Costa and Alvaro Morata who can run in behind the defence and cause the European champions some problems to deal with at the back and trouble Virgil van Dijk and co.
Furthermore, Liverpool haven't kept a single clean sheet at Anfield throughout the group stage. As evidenced from the matches throughout the season, Atletico Madrid will get some really good opportunities to score at Anfield and the Wanda Metropolitano and converting those chances will be crucial for the Spanish side.