I'm sure that Shakhtar - Zenit will be under 2.5 (our first choice striker Kerzhakov, winger Anyukov and team leader Denisov are injured and won't be playing today = no goals for Zenit; and Shakhtar won't be able to score 3)
Marseille against Arsenal is a coin flip with better odds on Marseille. X,2 is a pretty bad decision.
I agree with you on Olympiakos, from what I saw they are a solid team with good offensive line.
I'm going with Zenit u1.5 and Olympiakos - Dortmund over 2.0 @ 2.12