CREATE TABLE table_31076 ("Week of" TEXT, "Tournament" TEXT, "Champion" TEXT, "Runner-up" TEXT, "Semifinalists" TEXT, "Quarterfinalists" TEXT)

Who became the champion for the 1984 Grand Prix where Marty Davis was the runner-up?
SELECT "Champion" FROM table_31076 WHERE "Runner-up" = 'Marty Davis'
SELECT "Champion" FROM "table_31076" WHERE "Runner-up" = 'Marty Davis'