user: Question: when is the opponent Lyoto Machida?
Columns: ['Result', 'TUF Competitor', 'Opponent', 'Method', 'Event', 'Date']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Loss', 'Joe Stevenson', 'B.J. Penn', 'Submission (Rear Naked Choke) at 4:02 of round 2', 'UFC 80: Rapid Fire', 'January 19, 2008']
SQL:

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