Without doubt, Union Berlin's performance this season have been outstanding. They so far won 6 out of the 9 games they have played. While, their match between Dortmund will be an interesting one. Union Berlin have high chances of winning, Although, it quite certain that it won't be an easy winning. But, I will like to see Union Berlin win inorder for them to maintain occupying the first position on the standings.
Even if Union Berlin loses in this round, they will most likely still remain in first place, since Dortmund will not have three points to overtake Union Berlin, and Freiburg will play with Bayern in this round and most likely will also lose. Not so long ago, Union Berlin hosted Bayern at home and the match ended 1:1, so the team can score points with strong teams too. But the odds of 2.3 for Borussia looks very tempting.
Union Berlin against Bayern Munich still takes a very long time it looks like the match will happen next year and I am very sure Union Berlin will get an easy win because Bayern Munich's strength does not increase and hopefully Union Berlin can get a win in this Bundesliga. At least they should try to defend their first position because it is very difficult to maintain the best position because there will be many opponents who will try to knock them down.