Even though both teams are currently out of CL places, the season has just started and there should not be any reason to panic for their fans. Both will probably end up qualifying easily - Serie A and Primera are too weak for such major upsets.
Juventus fans shouldn't panic indeed. Because they are getting better day by day and having a consistent performance these days also. They won their last two games in the Serie A and they managed to beat even Chelsea in the Champions League also.
But I can't say the same thing for Barcelona fans unfortunately. Because the team are playing very inconsistently recently and it seems really hard to predict the results of their games. They show a great performance once but later everything changes about them. They weren't able to do anything against Benfica for example. They are not in a trustworthy condition and the fans shouldn't have big expectations from them at least for now.