The first games of this season's Champions League main phase are going to be held on September 16th.
I would bet money on Arsenal and Borussia Dortmund winning as guests versus Athletic and Juventus. I don't think that Juventus is showing a good performance in the Serie A(they've won against Parma and Genoa, but I'm not impressed) . Tottenham and Villarreal might end in a draw(at least that's what I'm hoping for). Real Madrid and Benfica seem like absolute favorites against Marseille and Qarabag, but the team from Azerbaijan shouldn't be underestimated.
I totally don't care about the game between PSV Eindhoven and Union St. Gilloise. I haven't watched those teams and I don't plan betting money on the outcome.