Arsenal is now on 2nd place in Group D in Champions league. They often plays attacking formation 4-1-4-1 so I expect here over 2.5 goals. This season in CL they played 3 games over 2.5 goals in 4 rounds so far.
Dortmund is 1st place in Group D. Dortmund have great attackers: Aubumeyang, Kagawa, Reus. and other great names, I expect to score at least 2 goals in this game. They played 3 games in a row with over 2.5 goals in CL, I hope they tradition with over should continue and today.