user: Question: When did João Souza play?
Columns: ['Date', 'Tournament', 'Surface', 'Opponen', 'Score']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['July 18, 2005', 'Tarzana , USA', 'Hard', 'Alex Bogomolov, Jr.', '6–3, 6–2']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Opponen" = 'João Souza';