I think this is something that no team wants. Injuries to key players have a very negative impact on the team's performance, especially if it is an elite level competition such as the Champions League. This is the same as the injuries to Haaland and Kevin De Bruyne at City which will cause their performance to decline drastically. Inter have to face Atletico which is of course a difficult match. It will be interesting to see how Inzaghi will strategize to deal with this problem.
All teams manager have prepare with their squad for facing bad thing exactly main players injury, its very important how to manage teams keep balance level performance between regular and reserves players. I think Simone Inzaghi have alternative scheme when Lutaro Martinez get injury because still has Marcus Thuram with performance almost on the level with Martinez.
Learning from Pep guardiola when De Bruyne injury can manage well Manchester City performance in champion league by giving chance to other player fill in attacking midfielder and give good contributing help Manchester City qualify to of 16 round.
The coach will think about it and anticipate it, but the problem is whether what they have prepared can work well or not. The fact is that some clubs also experience difficulties when they have to play without their mainstay players even if only one player is absent. There needs to be a balance between the main players and the reserve players, and what I see now is where the reserve players have not been able to provide something good when they have to replace the role of the main players.
I'm not going to blame them, because the lack of minutes they get will also affect their performance. And I think there are very few options, because great players will definitely not want to be on the bench and just be a coating. in this case the touch of the game must be maintained, one of which is by rotating players.