CREATE TABLE table_name_23 (opponents VARCHAR, year VARCHAR, team VARCHAR)

Which Opponents have a Year of 1998 99, and a Team of aston villa?
SELECT opponents FROM table_name_23 WHERE year = "1998–99" AND team = "aston villa"
SELECT "opponents" FROM "table_name_23" WHERE "1998–99" = "year" AND "aston villa" = "team"