You are of course right, Liverpool could lose against Atalanta but I think Liverpool are the favourites. Atalanta has a fairly productive attack line and so far they have proven their abilities by scoring 12 goals in the group stage and 3 goals in the round of 16. Liverpool have to be aware of the possibility of defeat, that's can make them fail to win a semifinal ticket. So it is not certain which of the two they will qualify for the semifinals.
Liverpool have 3 matches in the Premier League before the Europa League quarter-final match against Atalanta, so maybe this could also affect the team in the Europa League, especially if several players get injured before the match. I'm support Liverpool to win that ticket, but not underestimating Atalanta.
It is very clear that Liverpool is the favorite team to win the match. Even, Liverpool is the favorite to win the UEL trophy. However, it is not impossible if Atalanta can defeat Liverpool, Atalanta isn't a weak team. But considering the quality of the players of all the lines, I am optimistic Liverpool will beat Atalanta in this round. Liverpool is one of the most productive teams, they scored many goals. But Liverpool must be careful with their defense because sometimes the defenders played inconsistently.
Jurgen Klopp needs to rotate the players on the starting line-up. I'm sure it won't be a bog problem for Liverpool. They have enough players to play in 3 matches in EPL, and then they will play against Atalanta in Europa League.
Most hope is normally on Liverpool because they are the ones with almost the highest performance and goals so far, and talking about their defence, they really need to hold it tight, but to me, I see nothing for them to fear in Atalanta because Atalanta also knows that their opponents are teams that are not simple to handle. When they look back and see what they did to Sparta Prague, they will also know that Liverpool are not for jokes.
Even though Liverpool has some slight issues with their defence, I am very sure Atalanta can’t make their way to the net. Even if they had the opportunity to get that chance, it would not be more than a goal, and I know for a home and away game, Liverpool will not give them less than eight goals, so to me, I have more hope for them in the league, but I am not that sure they will go with the trophy this season. So with patience, we will see how Atalanta will be badly beaten in the field soon.