Table: anastasija_sevastova_tournaments
Columns: date
tournament
surface
opponent
score

Question: Who is the opponent for the game played on august 20, 2006?
SQL: SELECT "opponent" FROM anastasija_sevastova_tournaments WHERE "date" = 'august 20, 2006'

Question: On which Surface will Estrella Cabeza Candela play?
SQL: SELECT "surface" FROM anastasija_sevastova_tournaments WHERE "opponent" = 'estrella cabeza candela'