Atalanta is among the teams I'm tipping to win the champions league this season if it misses Liverpool and Barcelona. Like you said, Atalanta is in their best form, even better than last season when they disgraced Bayern Leverkusen in the Europa League final. I see danger for Real Madrid because they need to win that match to remain in the round of 16 automatic qualification because PSG is seriously following them. Using the performance Madrid, I will bet Atalanta to win that match
In Serie A, Atalanta played consistently, even in all the matches they played, they got positive results and won their last five matches, it is not impossible that in the Champions League they will definitely be able to provide a victory making Atalanta in 5th position in the Champions League standings and they are also undefeated in their last five matches, so in my opinion, Atalanta is likely to be able to face Liverpool or Barcelona in the next match.
You obviously understand why I feel Atalanta may likely edge Real Madrid in their champions league encounter. They are consistent in both the Italian Seria A and the champions league. They are playing in very high spirit and in matches such as the one against Real Madrid is when you will see the Nigerian Super Star Lukeman Ademola in action. He is a key figure in the team and will not hesitate to score Real Madrid when the opportunity arise.
If Atalanta will play Liverpool or Barcelona, that will be at later stage of the completion. Such encounter will be very interesting because those are the teams we'll positioned to win the trophy.