The point is that all eyes will be on Mbappe; Atalata defenders wouldn't give Mbappe any chance to make some deadly move to score on his first debut as a Real Madrid player. Real Madrid will have the match dominated, not giving Atalanta much player opportunity. I doubt if Atalata will pull a surprise shock to us by winning against Real Madrid as they did against Leverkusen.
The formation of Ancelotti remains the same. Real Madrid is having the 4-3-3 while Atalanta will have 3-4-3
Atalanta uses a formation that usually occurs in Serie A. They use 4 midfielders, and this allows them to move up and down when pressed, to help the club's defense line so that it cannot be penetrated by Real Madrid's attackers.
However, indeed, if you look at the statistics of each player, Atalanta must be very alert to various combinations of attacks from Real Madrid. Not only about Mbappe, but also his combination with Vinicius JR and Rodrygo. This will be much sharper with the three of them in the front line. Also, their wingers and midfielders, there are Bellingham, Camavinga and Valverde. if you look at it, they are the world's top players with their striking strength and abilities. So, here Atalanta must fight extra, because this will be quite different from Leverkusen as their previous opponent in the UEFA Europa League.