My two boys were playing tennis for the first time and the youngest was being a really bad loser. As I was watching, I saw my eldest son relax and allow Phil to win.
Afterwards when Phil had beaten Matthew, he started to show off and I could see Matthew starting to feel angry and wanting to retaliate. I walked over to Matthew said quietly, “I saw what happened on the court - it takes a big person to do what you did to keep the peace”. He immediately smiled and was his old self again and the moment passed.