I'll say the same thing I said about the Europa League final between Atalanta and Leverkusen, both teams have a chance of winning. It's a final, anything can happen in a final. We all know what Real Madrid is when it comes to the champions League and we know that based on quality and history, Dortmund don't stand a chance, but all that rich history won't matter in  single all or nothing match.
Madrid is the better team with more quality and experienced players and that's why they're favourites, but as we also know, in football, the favourites don't always win.

The chances of Dortmund winning are very slim, but there's no way I won't give them a chance. They may go into the game and protect a 1-0 lead till the end of the match. We've seen these things before and we'll still see them again. Today might be one of those days, you never know.