user: Question: How many rounds is the fight against Michael Chavez?
Columns: ['Res.', 'Record', 'Opponent', 'Method', 'Round']
Types: ['text', 'text', 'text', 'text', 'real']
Sample row: ['Loss', '42-20', 'Andre Winner', 'Decision (unanimous)', 3.0]
SQL:

assistant: SELECT "Round" FROM "Table" WHERE "Opponent" = 'Michael Chavez';