Which championship has Roger Federer as an opponent on a clay surface in a year earlier than 2007?
CREATE TABLE "grand_slam_tournament_performance_timeli" (
  "outcome" text,
  "year" real,
  "championship" text,
  "surface" text,
  "opponent" text,
  "score" text
);
SELECT "championship" FROM "grand_slam_tournament_performance_timeli" WHERE "opponent"='roger federer' AND "surface"='clay' AND "year"<2007;