Chelsea should be underrated completely in the Champions League. They have no track record, just that once they won the CL against Guardiola doesn't mean they are not experts in the Champions League. Chelsea is not a contender and their is no hope for them. They didn't take Champions League seriously than English Premier league, what happened is that EPL was stronger and hotter for them. Everyone wants to do well in EPL at the same time this season. There is no great hope for Chelsea in the CL.
Actually, this cannot be confirmed from now on because it is possible that Chelsea will appear more in the Champions League than other teams like Dortmund. Because anything can still happen after the world cup for every team and even teams that are taken for granted can change for the better after the world cup. So it's really not worth it to underestimate now, especially since the second half of the season hasn't started yet and the Champions League round of 16 hasn't even started yet.
Right, I think all the teams that are in the Champions League at the moment are worth considering, there will only be gaps between them. I mean there is a percentage rate for each team for example. Chelsea will not beat Manchester City's title percentage but they cannot be underestimated because maybe it will make us regret having underestimated them. I believe there will be many surprises here.