Not sure about other sports, but at hockey games here, both countries' national anthems are performed. Some Americans have occasionally butchered the Canadian anthem or have displayed our flag upside down... which causes a fair bit of ill-feeling here.These days, it seems odd to me when the national anthem is sung prior to a sporting event, and it almost always is in professional sports. It would fit in at national-teams-level soccer match or an Olympic medal ceremony or when a military academy team was participating, but at an ordinary hockey game? We don't do it before a theater performance or a concert or a group dinner, so I'm not sure why we do it at sporting events. I also wonder whether it is done in Canada, or if the Canadian teams only have O Canada played when they are playing abroad?