Real Madrid's midfield is very strong. Every player in the midfield is talented and experienced. Madrid's strong performance has a lot to do with their midfielders. If Luka Modric is sidelined for the match against Manchester City, Madrid does not have a suitable replacement. Apart from Luka Modric, Ancelotti has to develop his match strategy. If the match strategy is good, maybe the Madrid team will not miss Modrich during the match.
I have no idea why many people keep mentioning Luka Modric, this guy is really overrated.
He's already old, you can see his performance isn't that good anymore like the last year. Real Madrid currently depends on Kroos and Valverde, there's no other player has stable performance like both of them. Ancelotti will put a big hope to Camavinga and Tchouameni for playing this big match, since it looks like a gambling, I don't really believe they will beat Manchester City.
Manchester City has De Bruyne, Gundongan, Rodri and Silva, four of them are in the same level like Kroos and Valverde.