user: Question: On what date did the match against Flavio Cipolla, played on a Clay surface, occur?
Columns: ['Date', 'Tournament', 'Surface', 'Opponent in the final', 'Score']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['July 20, 1998', 'Londrina', 'Clay', 'Paulo Taicher', '6–3, 6–4']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Surface" = 'Clay' AND "Opponent in the final" = 'Flavio Cipolla';