CREATE TABLE table_57628 ("Outcome" TEXT, "Date" TEXT, "Tournament" TEXT, "Surface" TEXT, "Opponent in the final" TEXT, "Score" TEXT)

In the surface of clay who was the opponent in the game resulting in a score of 6 4, 6 4?
SELECT "Opponent in the final" FROM table_57628 WHERE "Surface" = 'clay' AND "Score" = '6–4, 6–4'
SELECT "Opponent in the final" FROM "table_57628" WHERE "Score" = '6–4, 6–4' AND "Surface" = 'clay'