This year's Champions League has become quite competitive. Bayern Munich and Manchester City have very strong squads. And they are consistently playing well. In addition, Arsenal, Real Madrid, Barcelona, Real Sociedad Atlético Madrid and Inter Milan have performed very well. The four La Liga teams Barcelona, Real Madrid, Atletico Madrid and Sociedad have played well and will surely qualify for the knockout rounds. City, Munich and Madrid are considered to be the favorites for this year's title. However the road to qualifying for the Champions League final will not be easy for them.
But a lot of things can happen until these games for the knockout round finally begin. For teams like Real Madrid and Bayern Munich it is incredibly important that the key players stay healthy. It would really change a lot for one of those teams if for example Harry Kane gets injured or Bellingham gets injured. I think Manchester City, due to having so many midfielders with offensive potential, would be most able to have a plan in case Haaland is injured. For Bayern Munich it would be tough and for Real Madrid Bellingham is also irreplaceable.
You are right, Manchester City is dependent on Haaland, Munich is dependent on Kane's performance and Madrid is now dependent on Bellingham's performance. And if these players suffer injuries in the knockout round, it will become much more difficult for the teams to qualify for the quarter finals. Because almost every team in the knockout round will be strong. So it will be much more difficult to win without a full strength squad. However, if clubs are not too unlucky their key players will not suffer injuries. Because Kane, Bellingham and Haaland are all fit enough.