SCHEMA:
CREATE TABLE table_1918850_2 (surface VARCHAR, championship VARCHAR, score_in_the_final VARCHAR)
USER:
state the number of surface where championship is australian open and score in the final is 6–3, 4–6, 11–9

QUERY:
SELECT COUNT(surface) FROM table_1918850_2 WHERE championship = "Australian Open" AND score_in_the_final = "6–3, 4–6, 11–9"