Udinese has been playing just similar to Atalanta seasons ago when they suddenly rose in Serie A. More impressive, Atalanta manage to continue it about 4 seasons later. So far in this season, Udinese are good but they are far away from what Atalanta have achieved recent years.
I don't think there will be big shocks in Serie A this season because Udinese are lack of many things to have stable performance in a long season. What surprise we can see is top four, not Scudetto. This season, two Milan clubs will be challenged by more clubs from Napoli, Atalanta to AS Roma and Lazio. I don't consider it is a shock if any team among Napoli, Atalanta or AS Roma win Scudetto in this season.
In Serie A, from time to time, some middle-class clubs can start a good season, not so long ago in Serie A there was a Chievo club, they could also have a promising start, but then there was always a decline. I don’t see how Udinese will be able to last the whole season, although the example of Leicester (when they won the Premier League) shows us that nothing is impossible. So far, Udinese is Serie A dark horse this season.
Udinese's performance has been very good this season, they only lost once and drew once in 8 matches that have been running. It's too soon I think to think about their fate in Serie A, although not a few people compare them to Leicester in the EPL first. In the next match they will face Atalanta who are currently ranked 2nd in the Serie A standings. This match could be a deciding factor for them whether they are still consistent with their good performances, or even be the beginning of their downfall this season.
Note: Besides Udinese, we also have another underdog in the Bundesliga, they are Union Berlin.