Football is a game of luck and skills. Sometimes you will do everything well and play nicely, but in the end you lose. That is when we say that luck is not with that person. In the other hand, one can be an expert in playing but fails to win.
I agree with you that football sometimes can be very unpredictable because sometimes the club that has the best performance of wining normally end up losing at the end, perhaps that's the reason why knowing the exact team that would win between France and Spain is not easy but however at the end of the match we will no the club that would emerge as the winner. However the other match that also seem very difficult to predict is the match between England and Netherlands, though at first considering the England squad I had a strong hope they would win Netherlands but I realized that anything could be possible on that match because sometimes the underestimated clubs normally turn out to be victorious at the end, so perhaps what do you believe will be the outcome of the match between Netherlands and England tomorrow?.