user: Question: Which Tournament has a Opponent of Piero Luisi?
Columns: ['Outcome', 'Date', 'Tournament', 'Surface', 'Opponent', 'Score']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Winner', '7 March 2005', 'Portugal F1, Faro , Portugal', 'Hard', 'Marcel Granollers', '6–2, 6–7 (3–7) , 6–3']
SQL:

assistant: SELECT "Tournament" FROM "Table" WHERE "Opponent" = 'Piero Luisi';