Table: tennis_match_stats_9
Columns: edition
round
date
partnering
against
surface
opponents
result

Question: For what round was the opponent nikola ćirić dušan vemić?
SQL: SELECT "round" FROM tennis_match_stats_9 WHERE "opponents" = 'nikola ćirić dušan vemić'

Question: What was the surface when the result was 6–7 (6–7) , 7–6 (9–7) , 6–7 (4–7) , 7–5, 3–6?
SQL: SELECT "surface" FROM tennis_match_stats_9 WHERE "result" = '6–7 (6–7) , 7–6 (9–7) , 6–7 (4–7) , 7–5, 3–6'