question: What is every surface with a score in the final of 6–4, 6–7 (1–7) , 6–7 (4–7) , 4–6?
answer: SELECT surface FROM table_23235767_1 WHERE score_in_the_final = "6–4, 6–7 (1–7) , 6–7 (4–7) , 4–6"
context: CREATE TABLE table_23235767_1 (surface VARCHAR, score_in_the_final VARCHAR)