Regarding the game between Dortmund and Mainz, I saw the odds for Mainz as worth taking the risk. We have a 15.25 rate for winning Mainz in this game which is really tempting for me, Dortmund lost many points this season and if they lose this game it's not surprising even if they need the full three points to win the league.
I feel it's worth taking the bite as Mainz always play the role of spoiler for someone who is comfortably performing or need a crucial win. I have lot of parlay bets messed up by them. If you check Mainz performances, they have beaten Bayern and Lepizig recently, so I personally wouldn't want to go against them for low odds.
For Dortmund it will be a title after a decade so they will push hard but I am sure it wouldn't be easy going against Mainz. Well not as easy as bookmakers are favouring Dortmund here ahead of the fixture.