There are football pitches everywhere in Mandalay. The interest seems to be higher there than in Yangon. We saw quite a few impromptu games too.
We saw this huge crowd gathered by a pagoda on the outskirts of the city and went to take a look. It was a group of about 10 high school kids playing soccer and there were about 500 people watching
If you are interested in football, it's a good talking point with the locals (especially Premier League).