CREATE TABLE table_51371 ("Week" FLOAT, "Date" CLOB, "Opponent" CLOB, "Result" CLOB, "Attendance" CLOB)

What opponent has an attendance of 20,456?
SELECT "Opponent" FROM table_51371 WHERE "Attendance" = '20,456'
SELECT "Opponent" FROM "table_51371" WHERE "Attendance" = '20,456'