user: Question: On what Date was the Opponent Panathinaikos?
Columns: ['Round', 'Date', 'Opponent', 'Score', 'Attendance', 'Report']
Types: ['text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['FR', '20 September', 'Dnipro', '0–0', 15431.0, 'BBC Sport']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Opponent" = 'Panathinaikos';