My child is looking forward to seeing two of his clmates fight what should I do?

My 9-year old son had a friend come over and his friend told him that there is going to be a fight between two of their clmates (both boys) during recess tomorrow. My son is very excited about seeing the fight between his two clmates and cannot stop talking about it to our family and it has gotten me very concerned. Should I inform the school principal about the planned fight or should I tell my child just to mind his own business and just play with his friends and avoid seeing the fight all together.