Eight players canter on to the pitch, tanned arms, taut muscles, hair curling over the collars of their polo shirts. It’s the first semi-final of the Argentine Open, the most prestigious tournament in the polo world, the one the players really want to win. This year the stakes are higher than usual. It may be the last open for Adolfo Cambiaso, the world’s number-one player for more than two decades and the sport’s greatest of all time.