I agree that Liverpool must be careful with Atalanta. The bad performance in Serie A doesn't reflect the possibility of Atalanta in UCL. They may have bad luck in the early matches in Serie A, but it doesn't mean they will have bad luck in UCL matches as well. Sometimes a certain team has a stronger motivation when they play in UCL or UEL. It can be caused by their good history in the competition or the prestige value of the competition.
They lost big to Atalanta at their home stadium Anfield last season in Europa League and this is a painful lesson for Liverpool. Meeting Atalanta again in this season is a good opportunity for Liverpool to prove that their defeat last season is simply an accident and they are actually stronger and better than Atalanta.
To beat Atalanta, Liverpool must avoid same attitude, too confident like the last season, and can reduce risk of counter attacks from Atalanta. It will help them to minimize risk of losing against this opponent one more time.
I'm a Liverpool fan and if I'm being honest, that stats about not conceding any goals so far is just good for the records. The real test is going to be how long this Liverpool team can go before they lose it. My guess? Pretty soon.
Liverpool are performing impressively with their new head coach Slot but all teams have to fail some day. Liverpool are good but not too strong like a dominating team so that they can have unbeaten season like Leverkusen last season. Soon Liverpool will lose their first match in this season and it can come from any opponent. Liverpool are not perfect and Slot has many things to do with his players in this season.