People here backing the reasonable at first sight low scoring game, however, i've self convinced myself otherwise lets see if you'd agree. 

Morocco's biggest strength is defending the midfield and they defend with 10 men but behind that midfield are 3 defensive liabilibies - Saiss, Mazraoui and Aguerd to an extent. Spain well known for their ball movement, surely they can get the ball between midfield and defense fairly often. 

At the same time Spain spend too long passing it around.. which gives a chance to Morocco's midfield to snatch the ball and send a long ball up field. Spain lost to Switzerland in UNL in a very similar fashion so why not. On the other hand Spain like to play ball out of defense and Japan's pressing did them over.. although i doubt Morocco will press high up at some point they may have to.

What i'm getting at is there are obvious weaknesses on both ends, naturally its questionable if Morocco got the quality to exploit them and even more so the desire to take a risk but those 3 i mentioned may be turned inside out 1 on 1, could be yellow cards, free kicks, a penalty.. unexpected events can and in my opinion will take this over the line