CREATE TABLE table_23408094_14 (tournament_at_which_lead_began VARCHAR2, player VARCHAR2)

At what tournament did pete sampras begin his lead?
SELECT tournament_at_which_lead_began FROM table_23408094_14 WHERE player = "Pete Sampras"
SELECT "tournament_at_which_lead_began" FROM "table_23408094_14" WHERE "Pete Sampras" = "player"