CREATE TABLE table_9731 ("Tournament" TEXT, "Surface" TEXT, "Week" TEXT, "Winner" TEXT, "Finalist" TEXT, "Semi finalists" TEXT)

Which Tournament has a Semi finalists of martina hingis joannette kruger?
SELECT "Tournament" FROM table_9731 WHERE "Semi finalists" = 'martina hingis joannette kruger'
SELECT "Tournament" FROM "table_9731" WHERE "Semi finalists" = 'martina hingis joannette kruger'