user: Question: Who was the opposing team played at Riverfront Stadium?
Columns: ['Week', 'Date', 'Opponent', 'Location', 'Time ( ET )', 'TV', 'Result', 'Record']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Sun. Sep. 10', 'Cleveland Browns', 'Three Rivers Stadium', '4:00pm', 'NBC', 'L 51–0', '0–1']
SQL:

assistant: SELECT "Opponent" FROM "Table" WHERE "Location" = 'Riverfront Stadium';