For sure they will be very careful as they know their skills and their power. However, since Crawford is more defensive than Spence, I think he would win this fight and will avoid getting hit by the heavy shots of Spence. This fight is very unpredictable, no sure winner here for sure but everyone has their own prediction. 
Yeah right, it's like these two will be an advantage when one got the first powerful hit against his opponent and that would be quickly followed up when there will be no response. This happened when we saw the fight between Donaire and Inoue where the fastest to throw a destructive punch and land will win. More likely this kind of scenario will also happened in this fight because both fighters are known to be fast and powerful and also they are skillful to have their own signature punches.