CREATE TABLE table_204_520 (id DECIMAL, "outcome" TEXT, "no." DECIMAL, "date" DECIMAL, "championship" TEXT, "surface" TEXT, "opponent" TEXT, "score" TEXT)

which opponent is listed previous to j rgen fassbender ?
SELECT "opponent" FROM table_204_520 WHERE id = (SELECT id FROM table_204_520 WHERE "opponent" = 'jurgen fassbender') - 1
SELECT "opponent" FROM "table_204_520" WHERE "id" = (SELECT "id" FROM "table_204_520" WHERE "opponent" = 'jurgen fassbender') - 1