CREATE TABLE table_71830 ("Date" TEXT, "Tournament" TEXT, "Surface" TEXT, "Opponent in the Final" TEXT, "Score in the Final" TEXT)

On which surface did Mathieu play against Antonio Vei ?
SELECT "Surface" FROM table_71830 WHERE "Opponent in the Final" = 'antonio veić'
SELECT "Surface" FROM "table_71830" WHERE "Opponent in the Final" = 'antonio veić'