What is the Surface of the court against Ivo Klec with a Score of 6–3, 6–3?
CREATE TABLE "singles_26_18_8" (
  "outcome" text,
  "date" text,
  "tournament" text,
  "surface" text,
  "opponent" text,
  "score" text
);
SELECT "surface" FROM "singles_26_18_8" WHERE "opponent"='ivo klec' AND "score"='6–3, 6–3';