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No team can be underestimated in the Champions League, but the favorite team can always be the favorite.
Favorite teams benefit from many factors, including squad depth and experience. The favored team can beat the favorite team, but this happens very rarely and only occasionally.
The favourites are reliable because in many ways they are different from the underdogs. Football fans, especially those who always follow the Champions League, will study every team that is favoured in their domestic league. The factors you mentioned are part of what they think about, even though in the end, the favourites can also slip up and make them fail.
The underdog team could qualify for the round of 16 or the quarter-finals, but it takes more hard work to reach the semifinals and above. Favorite teams are more likely to be in the final than all underdog teams, in fact most of them will only end up in the playoffs or the last 16. But like you said, we'll see.
Or do you want to say that your favourite team that you didn't mention here can make it to the final?
Madrid you might want to mention or Barca. Or maybe Manchester City. This time with the new format it is not certain which one or both of them will make it to the final.