user: Question: What was the Opponent before Week 11 with an Attendance of 63,571?
Columns: ['Week', 'Date', 'Opponent', 'Result', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'September 25, 1960', 'at San Francisco 49ers', 'W 21–19', '44,598']
SQL:

assistant: SELECT "Opponent" FROM "Table" WHERE "Week" < 11.0 AND "Attendance" = '63,571';