I've been going to Dinamo Zagreb games since 1992, and more than once i had high hopes, but somehow they managed to mess it up each year, with 2 exceptions, in the late 90s and last year.
That being said, this Dinamo Zagreb really looks confident, more mature and a team with a plan. Dinamo always had very talented players, but this year they managed to keep all their best players except Sunjic who they sold way to cheap (imho he was 2nd or 3rd most important Dinamo player). I didn't say that they cant be 2nd, of course they can, but personally i think it would be very hard and for me 3rd spot would be good too. Atalanta played awful game and Dinamo was brilliant, but Dinamo can also play like crap, and i simply don't want to be caught in euphoria after only 1 round.
Experience and traditionally a winning mentality goes a long way in the Champions League. I don't know how far Dinamo can go, if they can advance from the Group stage. I remember a few years ago when they were in the same group as Juventus they didn't win a single point. Can't remember if they scored more than a few goals.
From a realistic point of view do you think they have what it takes to to repeat the performance against Atalanta?
To be honest, i am not sure that they can repeat this performance, what we saw the other night was maybe best Dinamo game in many years.
Dinamo had some good performances against strong opponents in the past like 0:0 against Man Utd @Old Trafford in 1999 ( strongest ManUtd ever, they won CL previous season), 2 CL wins in 1998 (against Porto and Ajax), that 2:1 win against Arsenal few years ago, but i think they never dominated like against Atalanta.
It is right what you said about winning mentality, and Dinamo certainly lacked that, despite domination in national championship, but they might got back on the track previous season, when they managed to go through next round in Europe, first time in almost 50 years or so. That obviously gave them confidence boost.
For Dinamo to finish 2nd, beside them keep playing good, it is also needed that Man City keep beating Shakhtar and Atalanta, taking all points from them. But as i said before, i don't want to jump on hype train after 1st round, too many games left and i know that things can get complicated very fast.