Table schema:
CREATE TABLE table_name_51 (runner_s__up VARCHAR, margin_of_victory VARCHAR, tournament VARCHAR)

Question: What is Runner(s)-Up, when Margin of Victory is 1 Stroke, and when Tournament is Joburg Open 1?
SQL: SELECT runner_s__up FROM table_name_51 WHERE margin_of_victory = "1 stroke" AND tournament = "joburg open 1"