user: Question: Who is the opponent in the fight of 1 round when the record is 18-7?
Columns: ['Res.', 'Record', 'Opponent', 'Method', 'Event', 'Round']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Loss', '19-12', 'Duane Ludwig', 'TKO (strikes)', 'Strikeforce: Payback', '1']
SQL:

assistant: SELECT "Opponent" FROM "Table" WHERE "Round" = '1' AND "Record" = '18-7';