CREATE TABLE table_21584646_10 (runner_up VARCHAR2, champion VARCHAR2)

Who is the runner up for the champion of john mcenroe 6 2, 6 3?
SELECT runner_up FROM table_21584646_10 WHERE champion = "John McEnroe 6–2, 6–3"
SELECT "runner_up" FROM "table_21584646_10" WHERE "John McEnroe 6–2, 6–3" = "champion"