user: Question: Who was the visiting team on weeks under 12 and at Sports Authority Field at Mile High?
Columns: ['Week', 'Date', 'Visiting Team', 'Final Score', 'Host Team', 'Stadium']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [10.0, 'November 10', 'Oakland Raiders', '24–17', 'San Diego Chargers', 'Qualcomm Stadium']
SQL:

assistant: SELECT "Visiting Team" FROM "Table" WHERE "Week" < 12.0 AND "Stadium" = 'Sports Authority Field at Mile High';