user: Question: Who is the Opponent playing at 20:00 GMT at Camp Nou?
Columns: ['Date', 'Time', 'Competition', 'Opponent', 'Ground', 'Score']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['17 July 2007', '15:30 GMT', 'Friendly Match', 'China Olympics Team', 'Riscone di Brunico', '3-0']
SQL:

assistant: SELECT "Opponent" FROM "Table" WHERE "Time" = '20:00 GMT' AND "Ground" = 'Camp Nou';