CREATE TABLE table_15509 ("Date" CLOB, "Opponent" CLOB, "Score" CLOB, "Loss" CLOB, "Attendance" FLOAT, "Series" CLOB)

Who was the opponent when the series was at 1-3?
SELECT "Opponent" FROM table_15509 WHERE "Series" = '1-3'
SELECT "Opponent" FROM "table_15509" WHERE "Series" = '1-3'