คู่ต่อสู้ใครคือวันที่ 21 ไม่จำเป็นต้องใช้ทุกโต๊ะ
who was the opponent where the date was the 21st?It is not neccessary to use all the tables.
 table_21361:  "Date" [ text]  "Opponent" [ text]  "Venue" [ text]  "Result" [ text]  "Attendance" [ text]  "Competition" [ text] 
SELECT "Opponent" FROM table_21361 WHERE "Date" = '21st'