Buying TICKETS to Football games


Does anybody know how to get football tickets (on line or a ticket service) for a game? Specifically, next Sunday River vs Rosario.


Registered will sell tickets to most River matches a few days (2???) before without the fees of concerns catering to rich tourists. One can sign up for alerts on their site about when tickets go on sale. For particularly popular matches, it might not be the best bet. For concerts, they usually put tickets on sale at 10 AM, but I've never bought futbol tickets there.