This is a very good question. Sunday afternoon is the normal time when my playgroup gets together to have our fun games each week, but I'd never actually participated in a tournament on Sunday before last weekend. Then we decided to have one event (T2-mp) of the KY State tournament during our normal Sunday afternoon playtime. It wasn't very fun.
I'm not saying that God was punishing us for playing a tournament game then (although He might have been). However, I do remember that when I was a kid, I was taught that it was fine to play a sport for fun on Sunday if that helped you to relax. But that we shouldn't play in official games on Sunday because that changed it from being restful and relaxing to being competitive.
I appreciate your question because it reminded me of this teaching from my parents, and I think that in the future I will avoid playing in tournaments on Sunday.