Purchase a ticket and join the fans at a game at Ateneo Football Club. If there's nothing happening while you're in the area, you might like to check if there's a tour of the grounds.
This sporting facility is in Chascomus, a place that has so much on offer! Chascomus Lagoon, Historica Casa del Dr Raul Alfonsin 1957, and Los Libres del Sur Park are other good sightseeing choices nearby when you've finished up at Ateneo Football Club.