Table schema:
CREATE TABLE table_23408094_14 (tournament_at_which_lead_began VARCHAR, player VARCHAR, titles_won_at_point_of_lead VARCHAR)

Question: At which tournament did william renshaw begin his lead when he had won 7 titles?
SQL: SELECT tournament_at_which_lead_began FROM table_23408094_14 WHERE player = "William Renshaw" AND titles_won_at_point_of_lead = 7