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.
Since Union Berlin's next match at home is against Dortmund, it is indeed very possible for Union Berlin to win its 10th game of the season in the Bundesliga.
But Dortmund itself will also try to get a win because Dortmund are also eyeing a better position in the Bundesliga standings, although this season Dortmund are still less consistent in terms of their performance this season when compared to Union Berlin.