CREATE TABLE table_name_18 (opponent VARCHAR, partnering VARCHAR, surface VARCHAR, outcome VARCHAR)

Who was the Opponent partnering with Jordan Kerr, on a hard surface that was the winner?
SELECT opponent FROM table_name_18 WHERE surface = "hard" AND outcome = "winner" AND partnering = "jordan kerr"
SELECT "opponent" FROM "table_name_18" WHERE "hard" = "surface" AND "jordan kerr" = "partnering" AND "outcome" = "winner"