Red Star Belgrade travel poorly but they have an incredibly passionate, intimidating atmosphere at their home stadia. They are not to be underestimated in Belgrade.
Yes, passionate fans are a great addition, but they cannot win you the match. Serbian football is in a downfall for a long time, so I kind of ignored Red Star and thought they will get hammered.
I am pleasantly surprised by Red Star (back to back years in CL groups) so I plan to watch a game or 2 to see what that team is about and if they actually have some good players there.