CREATE TABLE table_31015 ("Team" TEXT, "Contest and round" TEXT, "Opponent" TEXT, "1st leg score*" TEXT, "2nd leg score**" TEXT, "Aggregate score" TEXT)

what was the name of the team opponent to elfsborg
SELECT "Team" FROM table_31015 WHERE "Opponent" = 'Elfsborg'
SELECT "Team" FROM "table_31015" WHERE "Opponent" = 'Elfsborg'