CREATE TABLE table_7767 ("Date" TEXT, "Tournament" TEXT, "Surface" TEXT, "Opponent in final" TEXT, "Score in final" TEXT)

What is the surface of the tournament with david nalbandian as the opponent in the final?
SELECT "Surface" FROM table_7767 WHERE "Opponent in final" = 'david nalbandian'
SELECT "Surface" FROM "table_7767" WHERE "Opponent in final" = 'david nalbandian'