The champions league list still at the group stage and nothing much should be expected, even lasts season when it was first adopted, nothing much happened at that stage, there was no much things to be intrigued about except that it felt like teams from different leagues coming to play a same league form as if it were a unifying league but beyond the league stage you will get to feel the heat and the whole rush that comes with the champions league.
The initial stages before the knockout stages are like that, as only a few teams that fall short of a certain position will be sent home due to not qualifying. But once you reach the knockout stages, where losses in the first and second legs are achieved, there's no barrier to elimination, so all teams will try their best to play better without feeling any pressure. Therefore, some unexpected surprises always occur, with teams that might not be favored because they win more than expected, or ordinary teams that manage to eliminate the favorites.