Leg-spinners Lloyd Pope (4/16 from ten overs) and Tom O’Connell (2/36) helped SA defend its moderate total of 155 and move through to Wednesday’s semi-finals.
Pope, a West End Redbacks rookie, has now taken 14 wickets to be the competition’s leading wicket-taker.
Earlier, SA opener Henry Dall made 42 but his dismissal was the first of seven wickets to fall for only 39 runs before Euan Fletcher (46 not out) and Ashley Eckermann (14) added 37 valuable runs for the tenth wicket.
SA’s Josh Hoffmann scored 61 for the Cricket Australia XI in its upset win over Queensland. Reigning champions Western Australia and NSW Metro also won through to the semi-finals.